This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Identify the correct Relative Humidity (%) of an air mass with saturation mixing ratio at 25°C is 20 grams and H2O vapour content is 5 grams1. 15%2. 30%3. 25%4. 50% |
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Answer» Correct Answer - Option 3 : 25% Relative Humidity (%): The relative humidity in an air parcel is defined as the ratio of the amount of water vapor actually in the air to the maximum amount of water vapor required for saturation at a particular temperature.
Given data
Calculation
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| 2. |
Which one of the following pairs is not correctly matched?1. First World Climate Conference - 19792. First Earth Summit - Agenda 213. Earth Summit + 5 - 19974. Carbon Trade - Montreal Protocol |
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Answer» Correct Answer - Option 4 : Carbon Trade - Montreal Protocol The correct answer is Carbon Trade - Montreal Protocol.
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| 3. |
In India, cultivation of which of the following crops is almost exclusively concentrated in southern states?1. Tea2. Bamboo3. Coffee4. Cotton |
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Answer» Correct Answer - Option 3 : Coffee The Correct Answer is Coffee.
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| 4. |
Which type of soil is best for the cultivation of sunflower?1. Loamy Soil2. Regur Soil3. Clay Loamy Soil4. Light Grid Soil |
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Answer» Correct Answer - Option 2 : Regur Soil The correct answer is Regur Soil.
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| 5. |
Which of the below mentioned regions exhibit less seasonal variations ?A. TropicsB. TemperatesC. AlpinesD. Both (a) & (b) |
| Answer» Correct Answer - a | |
| 6. |
What is common to the techniques (i) in vitro fertilisation, (ii) Cryopreservation and (iii) tissue culture?A. All are in situ conservation methodsB. All are ex situ conservation methodsC. All require ultra modern equipment and large spaceD. All are methods of conservation of ex- tinct organisms |
| Answer» Correct Answer - b | |
| 7. |
A diene on reductive ozonolysis produces two moles of ethanal and one mole of propan -1,3-dial How many geometrical isomer (s) is/are possible for the diene?A. 2B. 3C. 4D. 6 |
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Answer» Correct Answer - B The diene is `CH_(2)CH=CH-CH_(2)-CH=CHCH_(3)`. |
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| 8. |
'Generally high temperature is favourable for chemisorption.' Why ? |
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Answer» [Hint : To provide energy of activation.] |
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| 9. |
Kjeldahl method cannot be used for :(3) CH3–CH2–CH2–C≡N |
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Answer» Answer: (1) Kjeldahl method is not applicable to nitro or diazo groups present in the ring, as nitrogen atom can't be converted to ammonium sulfate under the reaction conditions. |
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| 10. |
Name the catalyst used in the following process :(a) Haber's process for the manufacture of NH3 gas.(b) Ostwald process for the manufacture of nitric acid. |
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Answer» [Hint : (a) Finely divided Fe/FeO, MO as promoter. |
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| 11. |
Why gas masks are used by miners in coal mines while working ? |
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Answer» [Hint : To absorb poisonous gases.] |
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| 12. |
Assertion: It has been found that for hydrogenation reaction the catalytic activity increases from group 5 to group-11 metals with maximum activity being shown by groups 7-9 elements of the periodic table. Reason: For 7-9 group elements adsorption rate is maximum. (1) Both assertion and reason are correct and reason is correct explanation of assertion. (2) Both assertion and reason are correct and reason is not correct explanation of assertion. (3) Assertion is true & reason is false. (4) Both are incorrect |
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Answer» Answer: (1) Both assertion and reason are correct and reason is correct explanation of assertion. |
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| 13. |
For the following Assertion and Reason, the correct option is Assertion : For hydrogenation reactions, the catalytic activity increases from Group 5 to Group 11 metals with maximum activity shown by Group 7-9 elements.Reason : The reactants are most strongly adsorbed on group 7-9 elements. (1) Both assertion and reason are true but the reason is not the correct explanation for the assertion. (2) Both assertion and reason are false. (3) Both assertion and reason are true and the reason is the correct explanation for the assertion. (4) The assertion is true, but the reason is false. |
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Answer» Answer is (4) The assertion is true, but the reason is false. Answer is (4) |
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| 14. |
Assertion: It has been found that for hydrogenation reaction the catalytic activity increases from group5 to group-11 metals with maximum activity being shown by groups 7-9 elements of the periodic table. Reason: For 7-9 group elements adsorption rate is maximum. (1) Both assertion and reason are correct and reason is correct explanation of assertion. (2) Both assertion and reason are correct and reason is not correct explanation of assertion. (3) Assertion is true & reason is false. (4) Both are incorrect |
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Answer» (1) Both assertion and reason are correct and reason is correct explanation of assertion. |
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| 15. |
The total number of 3-digit numbers, whose sum of digits is 10, is _______. |
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Answer» Let three digit number is xyz x + y + z = 10 ; x ≥ 1, y ≥ 0 z ≥ 0 ..... (1) Let T = x – 1 ⇒ x = T + 1 where T ≥ 0 Put in (1) T + y + z = 9 ; 0 ≤ T ≤ 8, 0 ≤ y, z ≤ 9 No. of non negative integral solution = 9+3–1 C3 –1 – 1 (when T = 9) = 55 - 1 = 54 |
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| 16. |
In a Young’s double slit experiment, 16 fringes are observed in a certain segment of the screen when light of a wavelength 700 nm is used. If the wavelength of light is changed to 400 nm, the number of fringes observed in the same segment of the screen would be(1) 28 (2) 24 (3) 30 (4) 18 |
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Answer» Answer is (1) 28 N1λ1 = N2λ2 16 × 700 = N2 × 400 ⇒ N2 = 28 Just use this formula and solveN1λ1 = N2λ2 16 × 700 = N2 × 400 ⇒ N2 = 28 |
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| 17. |
Let a,b,c,d and p be any non zero distinct real numbers such that (a2 + b2 + c2)p2 – 2(ab + bc + cd)p + (b2 + c2 + d2) = 0. Then : (1) a,c,p are in G.P. (2) a,c,p are in A.P. (3) a,b,c,d are in G.P. (4) a,b,c,d are in A.P. |
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Answer» (3) a,b,c,d are in G.P. (a2 + b2 + c2)p2 + 2(ab + bc + cd)p + b2 + c2 + d2 = 0 (a2p2 + 2abp + b2) + (b2p2 + 2bcp + c2) + (c2p2 + 2cdp + d2) = 0 (ab + b)2 + (bp + c)2 + (cp + d)2 = 0 This is possible only when ap + b = 0 and bp + c = 0 and cp + d = 0 p = -b/a = -c/b = -d/c or b/a = c/b = d/c ∴ a,b,c,d are in G.P. |
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| 18. |
For the vectors \(\rm \vec a = -4\hat i + 2\hat j\), \(\rm \vec b =2\hat i + \hat j\) and \(\rm \vec c = 2\hat i + 3\hat j\), if \(\rm \vec c = m\vec a + n\vec b\), then the value of m + n is:1. \(\frac{1}{2}\)2. \(\frac{3}{2}\)3. \(\frac{5}{2}\)4. \(\frac{7}{2}\) |
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Answer» Correct Answer - Option 3 : \(\frac{5}{2}\) Concept: If two vectors \(\rm \vec a = {a_1}\hat i + {a_2}\hat j+{a_3}\hat k\) and \(\rm \vec b = {b_1}\hat i + {b_2}\hat j+{b_3}\hat k\) are equal, then a1 = b1, a2 = b2 and c1 = c2.
Calculation: We have \(\rm \vec c = m\vec a + n\vec b\). ⇒ 2î + 3ĵ = m(-4î + 2ĵ) + n(2î + ĵ) ⇒ 2î + 3ĵ = (-4m + 2n)î + (2m + n)ĵ Equating the scalar coefficients, we get: -4m + 2n = 2 ... (1) 2m + n = 3 ... (2) Multiplying equation (2) by 2 and adding to equation (1), we get: 4n = 8 ⇒ n = 2 Using either of the equations above, we also get: m = \(\frac12\) ∴ m + n = 2 + \(\frac12\) = \(\frac{5}{2}\). |
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| 19. |
If \(\rm \vec A = 4\hat i +3\hat j+ \hat k\) and \(\rm \vec B = 2\hat i -\hat j+2 \hat k\), then the unit vector N̂ perpendicular to the vectors \(\rm \vec A\) and \(\rm \vec B\), such that \(\rm \vec A\), \(\rm \vec B\) and N̂ form a right handed system, is:1. \(\rm \frac{1}{\sqrt{185}}\left(7\hat{i}-6\hat{j}-10\hat{k}\right)\)2. \(\rm \frac{1}{7}\left(6\hat{i}+2\hat{j}+3\hat{k}\right)\)3. \(\rm \frac{1}{\sqrt{21}}\left(2\hat{i}+4\hat{j}-\hat{k}\right)\)4. \(\rm \frac{1}{\sqrt{21}}\left(-2\hat{i}-4\hat{j}+\hat{k}\right)\) |
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Answer» Correct Answer - Option 1 : \(\rm \frac{1}{\sqrt{185}}\left(7\hat{i}-6\hat{j}-10\hat{k}\right)\) Concept:
Calculation: We have \(\rm \vec A = 4\hat i +3\hat j+ \hat k\) and \(\rm \vec B = 2\hat i -\hat j+2 \hat k\). Therefore, their cross product will be: \(\rm \vec A\times\vec B=\begin{vmatrix} \rm \hat i & \ \ \ \rm \hat j & \rm \hat k \\ 4& \ \ \ 3&1\\2&-1&2\end{vmatrix}\) Expanding along R1, we get: = (6 + 1)î + (2 - 8)ĵ + (-4 - 6)k̂ = 7î - 6ĵ - 10k̂ The magnitude of \(\rm \vec A\times \vec B\) is: \(\rm \left| \vec A\times\vec B\right|=\sqrt{7^2+(-6)^2+(-10)^2}\) = \(\rm \sqrt{49+36+100}\) = \(\rm \sqrt{185}\) The unit vector N̂ along \(\rm \vec A\times\vec B\) will be: N̂ = \(\rm \frac{\vec A\times\vec B}{\left| \vec A\times\vec B\right|}\) ⇒ N̂ = \(\rm \frac{1}{\sqrt{185}}\left(7\hat{i}-6\hat{j}-10\hat{k}\right)\). |
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| 20. |
Let a, b and c be the distinct non-negative numbers. If the vectors \(\rm \hat i + b\hat j + \hat k,\hat i + b\hat j, a\hat i + c^2\hat j + c\hat k\)lie on a plane, then which one of the following is correct1. c is the arithmetic mean of a and b 2. c is the geometric mean of a and b 3. c is the harmonic mean of a and b 4. c = 0 |
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Answer» Correct Answer - Option 2 : c is the geometric mean of a and b Concept: If G is the geometric mean of the numbers a and b and is given by ⇔ G = \(\rm \sqrt {ab}\)
Calculation: Given, \(\rm \hat i + b\hat j + \hat k,\hat i + b\hat j, a\hat i + c^2\hat j + c\hat k\) are coplanar ∴\(\rm \left | \begin{array}{ccc} 1 & b & 1 \\ 1 & b & 0 \\ a & c^2 & c \end{array} \right | =0\) ⇒ 1(bc) - b (c) + 1(c2 - ab) = 0 ⇒ c2 = ab ⇒ c = \(\rm \sqrt {ab}\) Hence, option (2) is correct. |
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| 21. |
If the vectors \(\rm \rm (- \hat i-2 x \hat{j}-3 y \hat{k}) \ and \ (\rm \hat i-3 x \rm\hat j-2 y \rm\hat{k})\)orthogonal to each other, then what is the locus of the point (x, y)? 1. a straight line2. An ellipse3. A circle 4. A parabola |
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Answer» Correct Answer - Option 3 : A circle Concept: If vectors a and b are orthogonal, then \(\rm \vec a.\vec b\) = 0 Equation of circle: x2 + y2 = r2, where r = radius
Calculation: \(\begin{aligned} \rm &\rm (- \hat i-2 x \hat{j}-3 y \hat{k})(\rm \hat i-3 x \rm\hat j-2 y \rm\hat{k})=0\\ &\Rightarrow(-1)(1)+(-2\rm x)(-3\rm x)+(-3\rm y)(-2 \rm y)=0\\ &\Rightarrow 6 \rm x^{2}+6\rm y^{2}=1\\ &\Rightarrow \rm x^{2}+y^{2}=(1 / \sqrt{6})^{2}\\ &\text { Locus of }\rm(x, y) \text { is a circle } \end{aligned}\) Hence, option (3) is correct. |
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| 22. |
What is the area of the triangle with vertices (0,2,2), (2,0,-1) and (3,4,0)? 1. 15/2 sq units2. 7/3 sq units3. 15 sq units4. 1/5 sq units |
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Answer» Correct Answer - Option 1 : 15/2 sq units Concept: Area of triangle when two vectors are given: \(\rm \frac12 \times |\vec {AB} \times \vec {AC}| \) Cross product: \(\begin{array}{l} \rm \vec{a}=x_{1} \hat{1}+y_{1} \hat{j}+z_{1} \hat{k}\\ \rm \vec{b}=x_{2} \hat{1}+y_{2} \hat{j}+z_{2} \hat{k} \\ \rm \vec{a} \times \vec{b}=\left|\begin{array}{ccc} \rm \hat{i} &\rm j &\rm \hat{k} \\ \rm x_{1} &\rm y_{1} & \rm z_{1} \\ \rm x_{2} & \rm y_{2} &\rm z_{2} \rm \end{array}\right| \end{array}\)
Calculation: Here, Let A = (0,2,2), B = (2,0,-1) and C =(3,4,0) AB = (2-0, 0-2, -1-2) = (2, -2, -3) and AC = (3-0, 4-2, 0-2) = (3, 2, -2) Area of triangle = \(\rm \frac12 \times |\vec {AB} \times \vec {AC}| \) \(\begin{array}{l} =\rm \frac{1}{2}\left|\begin{array}{ccc} \rm \hat i &\rm \hat j & \rm \hat k \\ 2 & -2 & -3 \\ 3 & 2 & -2 \end{array}\right| \\ =\frac{1}{2}|[\rm \hat i(4+6)+ \rm \hat j(-4+9)+ \rm \hat k(4+6)]| \end{array}\) =1/2(10 i + 5 j + 10 k) = 1/2 √(100 + 25 + 100) = 15/2 sq unit Hence, option (1) is correct. |
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| 23. |
What is the value of λ for which the vectors \(\rm \hat i-\hat j+\hat k, 2\hat i+\hat j-\hat k, \hat i\lambda-\hat j+\hat k \lambda \) are coplanar 1. 52. 43. 24. 1 |
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Answer» Correct Answer - Option 4 : 1 Concept: \(\text { Let } \overrightarrow{\mathrm{a}}=\mathrm{a}_{1} \overrightarrow{\mathrm{i}}+\mathrm{b}_{1} \overrightarrow{\mathrm{j}}+\mathrm{c}_{1} \overrightarrow{\mathrm{k}}, \overrightarrow{\mathrm{b}}=\mathrm{a}_{2} \overrightarrow{\mathrm{i}}+\mathrm{b}_{2} \overrightarrow{\mathrm{j}}+\mathrm{c}_{2} \overrightarrow{\mathrm{k}} \text { and } \overrightarrow{\mathrm{c}}=\mathrm{a}_{3} \overrightarrow{\mathrm{i}}+\mathrm{b}_{3} \overrightarrow{\mathrm{j}}+\mathrm{c}_{3} \overrightarrow{\mathrm{k}} \text { be the three vectors }\) Condition for coplanarity: \( \overrightarrow{\mathbf{a}} \cdot(\overrightarrow{\mathrm{b}} \times \overrightarrow{\mathrm{c}})=\left|\begin{array}{lll} \rm a_{1} & \mathrm{b}_{1} & \mathrm{c}_{1} \\ \mathrm{a}_{2} & \mathrm{b}_{2} & \mathrm{c}_{2} \\ \mathrm{a}_{3} & \mathrm{b}_{3} & \mathrm{c}_{3} \end{array}\right|=0 \) Calculation: Here, \(\rm \hat i-\hat j+\hat k, 2\hat i+\hat j-\hat k, \hat iλ-\hat j+\hat k λ \) are coplanar \(\begin{array}{l} \Rightarrow \left|\begin{array}{ccc} 1 & -1 & 1 \\ 2 & 1 & -1 \\ λ & -1 & λ \end{array}\right|=0\end{array}\) 1(λ - 1) + 1(2λ + λ) + 1(-2 - λ) = 0 λ - 1 + 2λ + λ + -2 - λ = 0 3λ - 3 = 0 λ = 0 Hence, option (4) is correct. |
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| 24. |
Find the vector and Cartesian equations of the plane passing through the point (–1, 3, 2) and perpendicular to each of the planes x + 2y + 3z = 5 and 3x + 3y + z = 0. |
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Answer» Let the d.r.’s of the normal to the plane passing through the point (–1, 3, 2) be A, B, C. So, eq. of plane is : A(x + 1) + B(y - 3) + C(z - 2) = 0 ...(i) As (i) is perpendicular to the planes x + 2y + 3z = 5 and 3x + 3y + z = 0 So, A + 2B + 3C = 0 ...(ii) and, 3A + 3B + 3C = 0 ...(iii) Solving (ii) and (iii), we get : A/(2 - 9) = B/(9 - 1) = C/(3 - 6) i.e., A/-7 = B/8 = C/-3 i.e., the d.r.’s are –7, 8, –3. By (i), -7(x + 1) + 8(y - 3) - 3(z - 2) = 0 i.e., 7x - 8y + 3z + 25 = 0, which is Cartesian equation. Also the vector equation of plane is, vector r.(7i - 8j + 3k) + 25 = 0 |
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| 25. |
A wire, which passes through the hole in a small bead, is bent in the form of quarter of a circle. The wire is fixed vertically on ground as shown in the figure. The bead is released from near the top of the wire and it slides along the wire without friction. As the bead moves from A to B, the force it applies on the wire is (A) always radially outwards. (B) always radially inwards. (C) radially outwards initially and radially inwards later. (D) radially inwards initially and radially outwards later. |
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Answer» (A) always radially outwards. Initially bead is applying radially inward normal force. During motion at an instant, N = 0, after that N will act radially outward. |
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| 26. |
Let A and B be too sets containing four and two elements respectively then the number of subsets of set `AxxB` having atleast 3 elements isA. 219B. 256C. 275D. 510 |
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Answer» Correct Answer - A Given, `n(A) = 4 , n(B)=2 rArr n(A xx B) =8` Total number of subsets of set `(A xx B)= 2^(8)` Number of subsets of set `A xx B ` having no element `(i.e. Phi) = 1.` Number of subsets of set `A xx B` having one element `= "" ^(8)C_(1)` Number of subsets of set ` A xx B ` having two elements `= "" ^(8)C_(2)` ` therefore ` Number of subsets having alteast three elements `=2^(8)-(1+"" ^(8)C_(1)+"" ^(8)C_(2))=2^(8)-1-8-28` `=2^(8)-37=256-37=219` |
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| 27. |
What is a spreadsheet? How can we insert or delete any row or column in it? |
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Answer» A spreadsheet is a file that exists of cells in rows and columns and can help arrange, calculate and sort data. Data in a spreadsheet can be numeric values, as well as text, formulas, references and functions. Insert or delete a column 1. Select any cell within the column, then go to Home > Insert > Insert Sheet Columns or Delete Sheet Columns. 2. Alternatively, right-click the top of the column, and then select Insert or Delete. Insert or delete a row 1. Select any cell within the row, then go to Home > Insert > Insert Sheet Rows or Delete Sheet Rows. 2. Alternatively, right-click the row number, and then select Insert or Delete. |
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| 28. |
'Insert -> Page Break' is used to inserta) A break in a pageb) A new pagec) A new sheetd) A new break |
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Answer» (b) A new page 'Insert -> Page Break' is used to insert A new page. |
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| 29. |
When the text is printed or typed lengthwise, it is calleda) Landscapeb) Portraitc) Justifiedd) None of these |
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Answer» (a) Landscape When the text is printed or typed lengthwise, it is called Landscape. |
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| 30. |
What is the intersection of a column and a row on a worksheet called? A. Column B. Value C. Address D. Cell |
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Answer» Correct option: D. Cell |
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| 31. |
The intersection of a row and a column in a spreadsheet is known as ------a) Rangeb) Cellc) Formattingd) Label |
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Answer» (b) Cell The intersection of a row and a column in a spreadsheet is known as Cell. |
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| 32. |
Your grandmother completed eighty years of her age on August 16, 2017. Celebrating her 80th birthday was an event for the family.Describe the event in your words mentioning the following points:– preparations for the occasion – people who gathered – honour given to the grandmother – her reactions to the occasion – her personality – smart, witty, etc. – your reactions |
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Answer» Grandma Turns Eighty [Naren, XI A] Sixteenth August was a grand occasion for our family. My grandmother had turned eighty that day. We organised a family get-together. Messages had been sent to all my uncles, aunts and cousins. The ancestral home was decorated with flowers. A puja was performed in the temple. Then the main function began in the sitting room. It was a very cheerful occasion. All my uncles, aunts and cousins gathered under one roof. She was seated in a high arm chair. My uncle honoured her with a beautiful shawl. Then my parents presented her an almond coloured silk saree. Then came the turn of youngsters. She appreciated all the gifts presented to her and blessed us. She is still smart, witty and energetic. Words of wit and wisdom dropped like honey from her lips. Dressed in her usual orange coloured dress, she appeared like a divine personality. Since I was the youngest member of the family, I received love and . affection from everyone. Sometimes I felt it was my birthday. |
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| 33. |
The intersection point between a row and column is called _______. a) Row b) Column c) Table d) Cell |
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Answer» The intersection point between a row and column is called Cell. |
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| 34. |
The most common way to discover the type of a file, is to look at the ________ a) File name b) File extension c) Directory of file d) File size |
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Answer» b) File Extension The most common way to discover the type of a file, is to look at the File Extension. |
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| 35. |
Write last two digits of the number `3^(400)dot`A. 81B. 43C. 29D. 1 |
| Answer» Correct Answer - A | |
| 36. |
In a telephone system four different letter `P,R, S, T` and the four digits `3, 5, 7, 8` are used. Find the maximum number of "telephone numbers" the system can have if each consists of a letter followed by a four-digit number in which the digit may be repeated.A. 1024B. 2048C. `4^(5)`D. `5^(4)` |
| Answer» Correct Answer - A | |
| 37. |
Amrita is celebrating her 14th birthday. She wants to invite her friends and family members to the party. Which feature will she use to send the same invite to many people with different addresses without typing it again and again? a) Mail Merge b) Letter wizard c) Document Type d) None of these |
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Answer» Correct option: a) Mail Merge |
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| 38. |
Choose the appropriate answers for the following questions.Who did you invite to your birthday party? A) All my friends will come.B) All my friends will dance and sing. C) Something is there. D) Somebody is coming. E) You are welcome. |
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Answer» Correct option is A) All my friends will come |
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| 39. |
A team of 10 plyers is formed out of 22 players , if 6 particular players are always included and 4 particular players are always excluded then the number of ways in which the team can be formed, is-A. `.^(22)C_(10)`B. `.^(18)C_(3)`C. `.^(12)C_(4)`D. `.^(12)C_(8)` |
| Answer» Correct Answer - A | |
| 40. |
A team of 6 is to be formed from a class consists of 5 boys and 4 girls, such that at least 2 boys and 3 girls should be in the team. How many ways that can be done?1. 302. 503. 754. 45 |
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Answer» Correct Answer - Option 2 : 50 Concept:
Calculation: Selection of 2 boys out of 5 = 5C2 = 10 Selection of 3 boys out of 5 = 5C3 = 10 Selection of 3 girls out of 4 = 4C3 = 4 Selection of 4 girls out of 4 = 4C4 = 1 Now the selection can be done in the ways = 2 boys and 4 girls + 3 boys and 3 girls Hence number ways N = 5C2 × 4C4 + 5C3 × 4C3 Total number of ways = 10 × 1 + 10 × 4 = 50 ways |
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| 41. |
The number of ways in which 5 boys and 4 girls to sit around a table so that all the boys sit together is:1. 9!2. 5!5!3. 4!5!4. None of these |
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Answer» Correct Answer - Option 3 : 4!5! Concept: Arrangements of n different objects around a circle, then the number of arrangements is (n – 1)! Calculation: Given: All boys are to sit together So, All boys can be considered as a single group. ∴ Total no of students = 4Girls + 1Group = 5 The number of ways of arranging 5 students in a round table is (5 - 1)! = 4! Now, no of the ways of arranging 5 boys is 5! Hence, The total number of ways = 4!5! |
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| 42. |
The number of ways in which 4 boys and 4 girls can be arranged in a row so that no two girls and no two boys are together is1. (4!)22. 2(4!)23. 8!4. None of these |
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Answer» Correct Answer - Option 2 : 2(4!)2 Calculation: Given: 4 boys and 4 girls can be arranged in a row so that no two girls and no two boys are together. It means they can sit alternately Case-I: 1st person in the row is a boy. B1G1B2G2B3G3B4G4 The no. of ways in which the boys can be rearranged among themselves is 4!. Case-II:1st person in the row is a girl. G1B1G2B2G3B3G4B4 The no. of ways in which the girls can be rearranged among themselves is 4!. Hence, Total Number of ways = (4!)2 + (4!)2 = 2(4!)2 |
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| 43. |
Keshav has 9 friends, 4 boys and 5 girls. In how many ways can he invite them for birthday party, if there have to be exactly 3 girls in the invitees?(1) 120 (2) 260(3) 180(4) 160(5) None of these |
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Answer» Correct option is (4) 160 Keshav can invite exactly 3 girls but he can invite any no. of ways out for 4. ∴ Total no. of ways = \(5_{C_3} (4_{C_0} + 4_{C_1} + 4_{C_2}+ 4_{C_3}+ 4_{C_4})\) \(= \frac{5\times 4 \times 3!}{2!\times 3!}\times 2^4\) \(= 10 \times 16\) \(= 160\) Hence, Keshav can infinite there friends in 160 ways if there have to be exactly 3 girls in the invitees. |
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| 44. |
What is an ‘ogive’? |
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Answer» The cumulative frequency curve is called ‘ogive’. |
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| 45. |
What is a ‘open-end class’ in a frequency distribution? |
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Answer» If in a class, the lower or upper limits are not specified are called open classes. |
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| 46. |
The probability that a bomb hits the target is 1/4 Five bombs are aimed at the target. Find the probability that: (i) 3 bombs hit the target (ii) at the most two bombs hit the target. |
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Answer» Let x denote the number of bombs hit the target is a Binomial variate with the parameters n = 5, P = 1/4 = 0.25 and q= 1 – p= 1 – 0.25 = 0:75. The p.m.f is:- p(x) = ncx px qn-x : x = 0,1,2 n p(x)= 5cx (0.25)x (0.75)5-x x = 0,1,2……..5 (i) p(3 bombs hit the target) =p(x = 3) = 5c3 (0.25)3 (0.75)5-3 = 10 × 0.015625 × 0.5625 = 0.08789. (ii) p(at most two bombs hit the target) = p(x ≤ 2) = p(x = 0) + p[x = 1) + p(x = 2) = 5c0 (0.25)° x (0.75)5-0 + 5c1 (0.25)1 (0.75)5-1 + 5c2 (0.25)2 (0.75)5-2 = 1 × 1 × 0.2373 + 5 × 0.25 × 0.3164 + 10 × 0.0625 × 0.4218 = 0.2373 + 0.3955 + 0.2637 = 0.8965. |
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| 47. |
In a shoe shop, the highest sales of shoe size is 8. What would you conclude? |
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Answer» Modal(z) size is 8. |
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| 48. |
What are the limits of correlation co-efficient? |
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Answer» γ = ± 1 or -1 ≤ γ≤ 1. |
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| 49. |
If variance = 4 cm2 . Find the standard deviation. |
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Answer» Standard deviation = σ = √variance = √4 σ = 2 cm. |
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| 50. |
Find out quartile deviation and coefficient of quartile deviation of the following series: \( 28,18,20,24,30,15,47,27 \)(Ans. \( Q D=5.5 \), Coefficient of \( Q D= \) |
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Answer» First we arranged the data in ascending order: Now computing the quartile deviation (QD) and the formula is: Computing quartile 1 and quartile 3 as: Quartile 1 = 1/ 4 (n + 1)th term = 1/4 ( 8 + 1) = 1/4 × 9 = 2.25th term Quartile 3 = 3/4 (n+1 )th term = 3/4 (8+ 1) = 3/4 × 9 = 6.75 Computing the QD as: 6th term is 28 and adding to this 0.75 × (30 - 28), which is 1.5. the result is 29.5 Using the QD formula as: = 11 / 2 = 5.5 2. Computing the coefficient of quartile deviation as: Coefficient of quartile deviation = (Quartile 3 - Quartile 1) / (Quartile 3 + Quartile 1) Putting the values of the Quartile 3 and Quartile 1 in the above formula: = 11/ 48 = 0.229 |
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