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51.

1). 61602). 15403). 30804). 9240

Answer»

RATIO of selected to unselected candidates = 9 ? 2

Let the number of selected candidates be 9x and unselected candidates be 2X

TOTAL number of applied candidates = 9x + 2x = 11x

New ratio = 5 ? 1

Selected = 9x – 20

⇒ Unselected = (11x – 80) – (9x – 20) = 2x – 60

⇒ (9x – 20)/(2x – 60) = 5/1

9x – 20 = 10X – 300

x = 280

Total number of candidates who appeared for army = 11x = 11 × 280 = 3080

52.

Find the fourth proportional to 0.5, 1.12 and 1.3?1). 2.9142). 2.813). 2.1924). 2.912

Answer»

As we know that, FOURTH proportional = (b × C)/a 

Where a,b and c are the 1st, 2nd and 3rd elements of PROPORTION respectively a = 0.5, b = 1.12 and c = 1.3

(1.12 × 1.3)/0.5

1.456/0.5 = 2.912

53.

In a college, the ratio of boys and girls is 5 : 3 and the ratio of girls and teachers is 7 : 1. What is the ratio of students and teachers?1). 57 : 32). 54 : 13). 26 : 14). 56 : 3

Answer»

The RATIO of boys and girls is 5 : 3

NUMBER of girls = (3/8) × number of students

The ratio of girls and teachers is 7 : 1

Number of girls/ Number of teachers = 7/1

[(3/8) × Number of students]/Number of teachers = 7/1

Number of students/Number of teachers = 56/3

∴ The ratio of students and teachers 56 ? 3

54.

1). 1252). 1503). 62.54). 225

Answer»

THIRD PROPORTION can be GIVEN as 252/10 = 625/10

∴ The third proportion of 10 and 25 is 62.5

55.

The sum of the ages of 5 children born at the intervals of 2 years each is 60 years. What is the age of the youngest child?1). 4 years2). 8 years3). 10 years4). 12 years

Answer»

Let the AGE of children’ s be x, x + 2, x + 4, x + 6, x + 8

⇒ Sum of age = 60

⇒ x + x + 2 + x + 4 + x + 6 + x + 8 = 60

5X + 20 = 60

⇒ 5x = 40

⇒ x = 8

∴ Age of youngest child = x = 8 years
56.

Rs. 729 were distributed among 3 workers in the following ratio of 1/3 : 2/5 : 1/6. Find the money received by 1st worker.1). Rs. 1202). Rs. 1353). Rs. 2704). Rs. 324

Answer»

As given-

∴ Simplified ratio of 1/3 : 2/5 : 1/6 = 10 ? 12 ? 5.

One can see that 1st employee got 10 shares amongst 27 shares of RS. 729.

Money received by 1st worker = (10/27) × 729 = 270

∴ 1st worker received = 270 Rs.

∴ Answer is Rs. 270.
57.

The ratio of the wages of Sunny and Mickey is 2 : 3 and the ratio of the wages of Mickey and Vicky is 7 : 8. If the product of the wages of Mickey and Vicky is 50400. Find the difference of the square of the wages of mickey and Sunny?1). 236002). 245003). 250004). 26500

Answer»

Given that,

Ratio of the WAGES of SUNNY and Mickey = 2 : 3

Ratio of the wages of Mickey & VICKY = 7 : 8

⇒ Ratio of the wages of Sunny, Mickey and Vicky are 14 : 21 : 24

Let the wages of Mickey be 21X and that of Vicky be 24x

According to the question,

21x × 24x = 50400

⇒ 504x2 = 50400

⇒ x = 10

So, the wages of Mickey = RS. 210 and the wage of the Vicky is Rs. 240

So, the wage of Sunny = 210 × (2/3) = Rs. 140

∴ The required difference = (210)2 – (140)2 = 44100 – 19600 = 24500
58.

1). 10850002). 11750003). 12250004). 1245000

Answer»

GIVEN,

Ratio of Populations of villages X and Y = X ? Y = 34 ? 43

Ratio of Populations of villages X and Y if the population of village Y INCREASE by 125000 = X ? (Y + 125000) = 17 ? 24

X ? Y = 34 ? 43

⇒ X/Y = 34/43

⇒ Y = 43X/34

Now,

X ? (Y + 125000) = 17 ? 24

⇒ X/ (Y + 125000) = 17/24

⇒ X/ (43X/34 + 125000) = 17/24

24X = 43X/2 + 2125000

⇒ X = 850000

The population of village Y = 43 × 850000/34 = 1075000

∴ The population of village Y = 1075000

59.

A garrison of 3000 men has provision for 30 days. If after 10 days, they are reinforced by 1000 men, how long will the provisions last?1). 12 days2). 14 days3). 15 days4). 18 days

Answer»

After 10 days, the PROVISION is left for 3000 men and is for 20 days. when 1000 more men join, the total number in the garrison are 4000.

“If 3000 men can CONSUME FOOD in 20 days, then 4000 will consume it in how many days”

3000 men consume food in 20 days

1 man consume food in 20 × 3000 days (more days)

4000 men consume food in $(= \;\frac{{20 \times 3000}}{{4000}} = 15\;{\rm{days}})$

60.

Mr. Vivek divides Rs. 1703 such that 4 times the 1st share, thrice the 2nd share and twice the third share amount to the same. Then the value of the 2nd share is:1). Rs. 4522). Rs. 5243). Rs. 5204). Rs. 542

Answer»

FIRST Share is X

2nd share is y

3rd share is z

As per the Question

$4X = 3y = 3z = k $ 

x = k/4

y = k/3

z = k/3

x + y + z = 1703

k/4 + k/3 + k/3 = 1703

11k/12 = 1703

k = 20436/11

value of 2nd share is: k / 3 = 20436/33 = 619.27

61.

If u : v = v : w, then what is the value of u4 : v4?1). u2 : wv2). u2 : w23). u2 v : w34). u : w

Answer»

Given that,

u : v = v : w

v 2 = UW

v 4 = (uw)2

then,

u4 : v4 = u2 : w2
62.

Rahul spends some part of his income and saves the remaining part. The ratio of his expenditure and saving is 6 : 1. If Rahul’s income is Rs 42000, then what will be his expenditure (in Rs)?1). 340002). 300003). 320004). 36000

Answer»

INCOME = EXPENDITURE + savings

Income = 6 + 1 = 7 units = 42000

1 UNIT = 6000

∴ Expenditure = 6 units = 6 × 6000 = Rs. 36000
63.

1). 9432). 9023). 7794). 786

Answer»

Let the seven numbers be x, 3X, 7X, 12x, 13x, 21x and 23X respectively.

⇒ x + 3x + 7x + 12x + 13x + 21x + 23x = 3280

⇒ x = 3280/80 = 41

Sum of highest THREE numbers = 41 × (13 + 21 + 23) = 41 × 57 = 2337

⇒ The average of the highest three numbers = 2337/3 = 779

∴ The average of the highest three numbers = 779

64.

The ratio of the numbers of male and female workers in a farm having 320 workers is 9 : 11. What will be the new ratio if 8 female workers leave the work?1). 91 : 812). 17 : 203). 6 : 74). 7 : 9

Answer»

According to the given information,

Number of total workers in the farm = 320

Ratio of MEN and women = 9 : 11

Number of men workers = total number of workers $(\times \;\frac{{9}}{{9 + 11}})$

Number of men workers $(= \;320\; \times \frac{{9}}{{9 + 11}}{\rm{\;}} = {\rm{\;}}144)$

Number of female workers = 320 – 144 = 176

According to the given information,

8 female workers leave the work,

the remaining number of female workers = 176 – 8 = 168

New ratio of male to female workers = 144 : 168 = 6 : 7

Hence new ratio is 6 : 7
65.

Find the fourth proportion of following numbers∶ 1/3rd of 24, 4/5th of 15, 3/7th of 211). 15.52). 133). 13.54). 12.5

Answer»

CONVERT the number in decimal form-

1/3rd$ of 24 = 1/3 × 24 = 8

4/5th $of 15 = 4/5 × 15 = 12

3/7th $of 21 = 3/7 × 21 = 9

Fourth PROPORTION = 8 ? 12 ?? 9 ? x

8/12 = 9/x

x = 27/2 = 13.5

66.

What is the 4th proportional of 3, 8, 12,?1). 362). 263). 324). 16

Answer»

We know that,

a : b :: c : X

Then fourth proportional x = (bc)/a

From the GIVEN data,

∴ Fourth proportional x = (8 × 12)/3 = 32
67.

Find the mean proportional between 5 & 45 ?1). 352). 203). 154). 25

Answer»

As we KNOW that, mean proportional = √a × B

Where a and b are outer elements of proportion

a = 5 and b = 45 

√5 × 45 = 15

68.

X and Y are two alloys which are prepared by mixing zinc and aluminium in the ratio of 1 : 4 and 11 : 8 respectively. If equal quantities of alloys are melted to form a third alloy Z then what is the ratio of zinc and aluminium in alloy Z?1). 32 : 472). 37 : 583). 37 : 954). 74 : 95

Answer»
69.

Two whole numbers are such that the cube of first number exceeds the cube of second by 61 and the ratio of the numbers is 5 : 4. What is the value of larger number?1). 32). 43). 54). 6

Answer»

Let TWO number be 5x and 4X

According to the QUESTION,

⇒ (5x)3 - (4x)3 = 61

⇒ 125x3 - 64x3 = 61

⇒ 61x3 = 61

⇒x3 = 1

⇒ x = 1

∴ Largest number = 5x = 5 × 1 = 5
70.

The ratio of incomes of P and Q is 5 : 3. Ratio of income of Q and R is 5 : 2. If one-fourth of P’s income is Rs. 500 more than the R’s income, then what is the income (in Rs) of Q?1). 75002). 150003). 300004). 18000

Answer»

Given ratio of INCOME of P : Q = 5 : 3, Q : R = 5 : 2

⇒ In both the ratios, the common term is ‘Q’. Make the value with respect to ‘Q’ same in both the ratio

⇒ Multiply both numerator and denominator on other side of the ratio (P: Q) with 5 and of ratio (Q: R) with 3, we get

⇒ P: Q = (5 × 5): (3 × 5), Q: R = (5 × 3): (2 × 3)

⇒ P: Q = 25 : 15, Q : R = 15 : 6

⇒ Combining both the ratios we get, P : Q : R = 25 : 15 : 6

LET the incomes be 25x, 15x, 6x

⇒ From the condition, ¼ (25x) = 500 + 6x

⇒ (25x/4) - 6x = 500

⇒ (25x - 24X)/4 = 500

⇒ (x/4) = 500

⇒ x = 500 × 4 = Rs. 2000

∴ Q’s income = 15 × 2000 = Rs. 30000
71.

If \(\frac{a}{3} = \frac{b}{5} = \frac{c}{7}\), then find the value of \(\frac{{a + b + c}}{b}\)1). 1/52). 1/33). 34). 5

Answer»

We have

$(\FRAC{a}{3} = \frac{b}{5} = \frac{c}{7})$ 

⇒ a = 3b/5, and c = 7b/5

Hence,

$(\frac{{a + b + c}}{b}\frac{{a + b + c}}{b} = \frac{{\frac{3}{5}b + b + \frac{7}{5}b}}{b} = 3)$ 

72.

1). 36002). 18003). 24004). 1200

Answer»

Let SHARE of B = X/3

Total share = (1/2 + 1/3 + 1/4)x = 13x/12

Share of B out of 7800 = (x/3) / (13x/12) × 7800 = 4/13 × 7800 = 2400

Share of B (in Rs) = Rs. 2400

73.

1). 2402). 4803). 1204). 720

Answer»

Let the ratio of selected(x) to UNSELECTED candidates (y) = x/y = 3m/m

Then the TOTAL NUMBER of candidates = 3m + m = 4M

Also given that 60 less had APPLIED and 30 less selected, the ratio of selected to unselected would have been 5 : 1

⇒ 4m - 60 have been applied, 3m - 30 has selected,

Total number of unselected candidates = Total number of applied candidates – total selected candidates

Total number of unselected candidates = (4m – 60) – (3m – 30) = m - 30

From the given data,

Selected candidates/Unselected candidates = 5/1

(3m - 30)/(m - 30) = 5/1

3m - 30 = 5(m - 30)

2m = 120

m = 60

∴ total no of candidates = 4m = 4(60) = 240

74.

If 20% of A = 30% of B = 1/6 of C, then find A ∶ B ∶ C.1). 12 ∶ 15 ∶ 182). 15 ∶ 10 ∶ 183). 15 ∶ 12 ∶ 184). 18 ∶ 10 ∶ 12

Answer»

20% of A = 30% of B = 1/6 of C

⇒ 20/100 × A = 30/100 × B = 1/6 × C

⇒ A/5 = 3B/10 = C/6

⇒ A ? B ? C = 5 ? 10/3 ? 6 = 15 ? 10 ? 18
75.

The ratio of salary of ananya and Krish are in the ratio of 4 : 5. If after one year, the salary of each of them is increased by Rs. 5000, the new ratio becomes 67 : 71. What is Krish’s salary?1). Rs. 1960.752). Rs. 1079.783). Rs. 1023.984). Rs. 1057.23

Answer»

Let salary of Ananya be ‘4x’ and salary of Krish be ‘5x’

⇒ According to the condition GIVEN in the problem,

$(\frac{{4x + 5000}}{{5x + 5000}} = \frac{{67}}{{71}})$

⇒ 71(4x + 5000) = 67(5x + 5000)

⇒ 284x + 355000 = 335x + 335000

⇒ 51x = 20000

⇒ x = RS. 392.15

∴ Krish’s salary = Rs. 1960.75
76.

There are 3 type of chocolates A, B and C in the vending machine. Chocolates A, B and C are in the ratio of 1/63 ∶ 1/77 ∶ 1/99. If \(9\frac{1}{{11}}{\rm{\% }}\) of chocolate A, \(11\frac{1}{9}\%\) of chocolate B and \(14\frac{2}{7}{\rm{\% }}\) of chocolate C are sold. Then find remaining ratio of chocolates in the vending machine. 1). 5 ∶ 4 ∶ 32). 1 ∶ 2 ∶ 33). 7 ∶ 5 ∶ 34). 9 ∶ 5 ∶ 7

Answer»

Ratio of Chocolates A, B and C = 1/63 ? 1/77 ? 1/99 = 11 ? 9 ? 7

Quantity of the chocolates A after selling = 11 × 10/11 = 10

Quantity of the chocolates B after selling = 9 × 8/9 = 8

Quantity of the chocolates C after selling = 7 × 6/7 = 6

∴ Ratio of chocolates A, B and C in the VENDING machine after selling = 10 ? 8 ? 6 = 5 ? 4 ? 3
77.

A mixture of 30 liters of milk and water contains milk and water in the ratio of 7 : 3. How much water must be added to it. so that the ratio of milk to water be reserved i.e. 3 : 7?1). 40 ltr2). 45 ltr3). 42 ltr4). 49 ltr

Answer»

Milk contents in the mixture $(= \frac{7}{{10}} \TIMES 30 = 21\;{\rm{liters}})$

Water = 9 liters

In the new mixture, the ratio of milk to water is 3 : 7

In 21 liters of milk water is $(\frac{7}{3} \times 21 = 49\;{\rm{liters}})$

Water to be ADDED = 49 - 9 = 40 liters
78.

The number of 5 rupees and 2 rupees coins that Donald has are in the ratio 4 : 7. Find the total number of coins that Donald has if amount of money in form of 5 rupees is 42 rupees more than amount of money in form of 2 rupees.1). 422). 773). 704). 60

Answer»

Let the number of 5 rupees COINS and 2 rupees coins be 4T and 7T, respectively.

We know, amount of money in form of 5 rupees is 42 rupees more than amount of money in form of 2 rupees.

⇒ (4T × 5) – (7T × 2) = 42

⇒ T = 42/6 = 7

TOTAL number of coins = 4T + 7T = 11T = 77
79.

The angles in a quadrilateral PQRS are such that angle S is fourth proportional of angles P, Q and R. If the ratio of angles Q and P is 5 : 4, and angle S is 125°, find the measure of angle R.1). 90°2). 100°3). 108°4). 120°

Answer»

Angle S is FOURTH proportional of angles P, Q and R.

⇒ P/Q = R/S

Ratio of angles Q and P is 5 : 4, and angle S is 125°.

So, P/Q = 4/5

⇒ 4/5 = R/125

⇒ R = 4 × 25 = 100

MEASURE of angle R is 100°.

80.

If the cost price of 20 books is the same as selling price of 25 books, then the loss percentage is1). 202). 253). 224). 24

Answer»

Let the C.P. of each book be Rs. 1.

Total C.P. of 25 BOOKS = 25

S.P. of books = 20

Loss percent $(= \left[ {\frac{{25 - 20}}{{25}}} \right] \times {\RM{\;}}100)$

$(= \frac{5}{{25}} \times {\rm{\;}}100{\rm{\;}} = {\rm{\;}}20{\rm{\% }})$

81.

Some money is divided among A, B and c in such a way that 7 times A’s share, 9 times B’s share and 11 times C’s share are all equal. The ratio between the shares of A, B, C is1). 7 : 9 : 112). 11 : 9 : 73). 63 : 77 : 994). 99 : 77 : 63

Answer»

Let their SHARES be A, B and C respectively.

Given,

7A = 9B = 11C

⇒ A : B = 9 : 7

⇒ B : C = 11 : 9

The LCM of 7 and 11 is 77. Hence, we MULTIPLY the FIRST ratio by 11 and the second by 7.We have

A : B = 99 : 77

B : C = 77 : 63

Hence, A : B : C = 99 : 77 : 63
82.

Divide Rs. 960 among M, N and O so that M get (3/9)th of N's share and O gets (4/7)th of M's share. What is the share (in Rs) of O?1). 1202). 3603). 6304). 480

Answer»

Let the shares of M, N and O be REPRESENTED by m, n and o respectively.

According to given information,

M’s SHARE = m = 3n/9 = n/3

O’s share = o = 4m/7 = (4/7) × (n/3) = 4n/21

Ratio of their shares = m ? n ? o = (1/3) ? 1 ? (4/21) = 7 ? 21 ? 4

Share of O = 960 × [4/(7 + 21 + 4)] = Rs. 120

∴ Share of O = Rs. 120
83.

Find the fourth proportional to 250, 458, 125.1). 2202). 4523). 2294). 345

Answer»

As we know that, Fourth proportional = (B × c)/a 

Where a,b and c are the 1st, 2nd and 3rd ELEMENTS of proportion respectively

a = 250, b = 458 and c = 125

(458 × 125)/250

57250/250 = 229

84.

Find the mean proportional between 3 and 27.1). 52). 123). 184). 9

Answer»

LET the required NUMBER be X.

3 ? X = X ? 27

⇒ X2 = 3 × 27

⇒ X = 9

So, the mean PROPORTIONAL between 3 and 27 = 9

85.

Ramesh uses a weight of 930 gm instead of 1 kg and sells sugar on its cost price. What will be his profit percentage on selling 15 kg sugar?1). 9.212). 73). 7.534). 8.54

Answer»

Let the COST PRICE be RS. 1000 PER kg.

Selling price of 930 gm sugar instead of 1 kg = Rs. 1000

Selling price of 15 kg sugar same way = Rs. 15000

Cost price of 930 gm sugar = Rs. 930

So, cost of 930 × 15 = Rs. 13950

∴ Profit percentage = [(15000 - 13950)/13950] × 100 = 7.53%
86.

A person has 45 coins of 50p, 1 rupee and 2 rupee coins in ratio 6 : 2 : 1. Which of the following combinations will yield the same amount of total money (the order of is 25p, 50p and 1 rupee and the total number of coins).1). 6, 2, 1, 452). 6, 2, 1, 903). 6, 5, 3, 704). None of these

Answer»

ACTUAL money with the person = 0.5((6/9) × 45) + 1((2/9) × 45) + 2((1/9) × 45) = 15 + 10 + 10 = Rs. 35

Total money in FIRST case:

Total VALUE of coins = 0.25((6/9) × 45) + 0.50((2/9) × 45) + 1((2/9) × 45) = 7.5 + 5 + 10 = Rs. 22.50

Total money in Second case:

Total value of coins = 0.25((6/9) × 90) + 0.50((2/9) × 90) + 1((2/9) × 90) = Rs. 45

Total money in Third case:

Total value of coins = 0.25((6/14) × 70) + 0.50((5/14) × 70) + 1((3/14) × 70) = Rs. 35

In third case, the amount is same

87.

Monthly income of A and B are in the ratio of 4 ∶ 3 and their expenses bear the ratio of 3 ∶ 2. If each of them saves Rs. 6000 at the end of the month, then what is the monthly income of A?1). Rs. 120002). Rs. 240003). Rs. 300004). Rs. 60000

Answer»

Let the monthly income of A and B be 4x and 3X.

Let the monthly expenses of A and B be 3y and 2y.

Income = Expenditure + Saving

⇒ 4x = 3y + 6000----(1)

⇒ 3x = 2y + 6000----(2)

By solving eq. (1) and (2), we get

X = 6000 and y = 6000

Monthly salary of A = 4x = 4 × 6000 = 24000
88.

If the third proportional of 2(x2 – y2) and (xy2 + x2y) is [8(x + y)/(x – y)], then find the value of xy.1). 22). 43). 84). 16

Answer»

As we know, if a? B = b? c, then c is the THIRD proportional of a and b

Let a = 2(X2 – y2), b = (xy2 + x2y), c = [8(x + y)/(x – y)]

⇒ 2(x2 – y2) : (xy2 + x2y) = (xy2 + x2y) : [8(x + y)/(x – y)]

⇒ 2(x2 – y2) × [8(x + y)/(x – y)] = (xy2 + x2y) × (xy2 + x2y)

? (x2 – y2) = (x + y)(x – y)

⇒ 2(x + y)(x – y) × [8(x + y)/(x – y)] = xy(x + y) × xy(x + y)

16 × (x + y)2 = (xy)2 × (x + y)2

⇒ 16 = (xy)2

∴ xy = √16 = 4
89.

1). 92). 63). 124). 3

Answer»

Let the number of COINS be 3x, 2x, 3x respectively

Then total amount will be given by

3x × 1 + 2x × 0.5 + 3x × 0.1 = 12.9

⇒ 3x + x + 0.3x = 12.9

⇒ 4.3x = 12.9

⇒ x = 3

Number of 50 paise coins = 2x = 2 × 3 = 6

90.

The ratio of the income to the expenditure of a family is 10 : 7. If the family expenses are Rs. 11,200, then the savings of the family is1). Rs. 4,5002). Rs. 10,0003). Rs. 4,8004). Rs. 5,000

Answer»

LET the income and expenditures be Rs. 10X and Rs. 7X respectively

⇒ Given Expense is Rs. 11,200

⇒ 7x = 11,200

⇒ x = 11,200/7 = 1600

SAVING = income - expenditure

⇒ Saving = 10x - 7x

⇒ Saving = 3x

PUTTING the value of x in above we get

⇒ Saving = 3 × 1600

∴ Saving = Rs. 4,800
91.

What number must be added to each of 45, 13, 33 and 9 such that the resultant numbers are in proportion?1). 42). 33). 134). 12

Answer»

Let the number to be added be ‘m’, then according to the question,

$(\frac{{45 + m}}{{13 + m}} = \frac{{33 + m}}{{9 + m}})$

⇒ 405 + 9m + 45m + m2 = 429 + 33m + 13m + m2

⇒ 54m – 46m = 429 – 405

⇒ 8m = 24

⇒ m = 3

Since, the required ANSWER is 3.
92.

The ratio of number of males and females workers in a factory was 2 : 5 with total number of workers as 1400. If the ratio of females to males changed to 5 : 4 when 100 more females and a few more male workers joined the company, then what is the number of males who joined?1). 8042). 4083). 8404). 480

Answer»

LET the number of male and female WORKERS be 2x and 5x

⇒ 2x + 5x = 1400

7X = 1400, x = 200

Thus, number of female workers = 5x = 1000

⇒ Number of male workers = 2x = 400

⇒ Now the ratio of female to male changes to 5 : 4 when 100 more FEMALES and a few more male workers joined the company.

Let the number of male workers who joined be x.

⇒ Then, (1000 + 100)/ (400 + x) = 5 : 4

1100/ (400 + x) = 5 : 4

⇒ 4400 = 2000 + 5x

⇒ 5x = 2400

∴ x = 480

93.

Find the third proportional to 16 and 20.1). 242). 253). 324). 40

Answer»

Let the third proportional be x

16 ? 20 ? 20 ? x

⇒ 4/5 = 20/x

∴ x = 100/4 = 25

94.

If the third proportion of two numbers is 27 and the first number is 12, then find the 2nd number.1). 162). 183). 144). 20

Answer»

To find the third proportion we use a formula b² = AC where a and b are two numbers and C is the third proportion of them.

⇒ b² = ac

⇒ b² = 27 × 12

∴ b = 18
95.

1). 2 ∶ 32). 1 ∶ 33). 1 ∶ 44). 1 ∶ 2

Answer»

For cylinder A height is h1 and Volume is V1

Similarly,

For cylinder B height is h2 and Volume is V2

$(\frac{{{\rm{V1}}}}{{{\rm{V2}}}}{\rm{ = }}\frac{{{\rm{\PI (r1}}{{\rm{)}}^{\rm{2}}}{\rm{h1}}}}{{{\rm{\pi (r2}}{{\rm{)}}^{\rm{2}}}{\rm{h2}}}})$

$(\Rightarrow \frac{{\rm{5}}}{{{\rm{36}}}}{\rm{ = }}\frac{{{{{\rm{(r1)}}}^{\rm{2}}}}}{{{{({\rm{r2)}}}^{\rm{2}}}}}{\rm{ \TIMES }}\frac{{\rm{5}}}{{\rm{4}}})$

$(\Rightarrow \frac{{\rm{5}}}{{{\rm{36}}}}{\rm{ = }}\frac{{{{{\rm{(r1)}}}^{\rm{2}}}}}{{{{{\rm{(r2)}}}^{\rm{2}}}}}{\rm{ \times }}\frac{{\rm{5}}}{{\rm{4}}})$

$( \Rightarrow \frac{{{{{\rm{(r1)}}}^{\rm{2}}}}}{{{{{\rm{(r2)}}}^{\rm{2}}}}}{\rm{ = }}\frac{{\rm{5}}}{{{\rm{36}}}}{\rm{ \times }}\frac{{\rm{4}}}{{\rm{5}}})$

$(\Rightarrow \frac{{{{{\rm{(r1)}}}^{\rm{2}}}}}{{{{{\rm{(r2)}}}^{\rm{2}}}}}{\rm{ = }}\frac{1}{9})$

⇒ r1/r2 = 1/3

∴ Ratio of r1 and r2 is 1 ? 3

96.

A purse has Rs. 34.5 in the form of 1-rupee, 50-paise and 10-paise coins in the ratio of 6 ∶ 9 ∶ 10. Find the number of 10-paise coins.1). 102). 303). 204). 40

Answer»

Let TOTAL coins in the purse are x.

⇒ 1-rupee, 50-paise and 10-paise coins would be 6X, 9x and 10x respectively.

Total amount is Rs. 34.5

⇒ 6x × 1 + 9x × 0.5 + 10x × 0.1 = 34.5

⇒ 6x + 4.5x + x = 34.5

⇒ 11.5x = 34.5

⇒ x = 3

NUMBER of 10-paise coins = 10 × 3 = 30
97.

I am three times as old as my son. After 10 years hence, I will be twice as old as my son. The sum of our ages is1). 40 years2). 60 years3). 84 years4). 72 years

Answer»

⇒ Let the age of son be x

⇒ then age of FATHER = 3X

⇒ after 10 years father will be twice as old as son

⇒ Father age = 3x + 10

⇒ Son age = x + 10

⇒ 3x + 10 = 2(x + 10)

⇒ 3x + 10 = 2X + 20

⇒ x = 10

SUM of their ages = x + 3x

⇒ Sum of their ages = 10 + 30

∴ Sum of their ages = 40
98.

What number should be added to each of 7, 17, 22 and 47 so that the resulting numbers will be in proportion in the given order?1). 12). 33). 24). 4

Answer»
99.

1). 275 cm32). 40 cm33). 55 cm34). 220 cm3

Answer»

Volume of each BOX = 2 × 5 × 10 = 100 cm3

Volume of WATER transferred to the containers = 5 × 100 = 500 cm3

Let the VOLUMES of the containers be 5x, 9x and 11x. Then,

5x + 9x + 11x = 500

⇒ 25x = 500

⇒ x = 20

∴ Volume of third container = 11x = 11 × 20 = 220 cm

100.

If (7x – 3y) ∶ (4x + y) = 5 ∶ 4, then find the ratio x ∶ y.1). 7 ∶ 22). 9 ∶ 43). 13 ∶ 64). 17 ∶ 8

Answer»

Given,

⇒ (7x – 3Y) ? (4x + y) = 5 ? 4

⇒ [7(x/y) – 3] / [4(x/y) + 1] = 5/4

⇒ 28(x/y) – 12 = 20(x/y) + 5

⇒ x/y = 17/8

∴ The required ratio is 17 ? 8