Explore topic-wise InterviewSolutions in Current Affairs.

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.

Find the vectors from the origin to the intersection of the medians of the triangle whose vertices are A(5,2,1), B(-4,7,0) and C(5, -3,5)

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Solution :
Given thatA = (5,2,1), B = (-4,7,0)
C = (5,-3,5)
Then position vectors of A, B, C are
`5hat+2hatj`, `-4hati+7hatj`. `5hati-3hatj+5hatk` RESPECTIVELY
Let G be the point of intersection of the MEDIANS of the triangleABC.
Then the position of VECTOR G
= `((5hati+2hatj+hatk) + (-4hati+7hatj) + (5hati-3hatj+5hatk))/3`
`(6hati+6hatj+6hatk)/3` = `2hati+2hatj+2hatk`
2.

Differentiate (sinx)^(cosx) with respect to x.

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ANSWER :`y[cosx.cotx-SINX.log(sinx)]`
3.

(i) Prove that: ""^(n)P_(r) = ""^(n-1)P_(r) + r. ""^(n-1)P_(r–1) (ii) If ""^(20)C_(r+2) = ""^(20)C_(2r–3) find ""^(12)C_(r) (iii) Find the ratio ""^(20)C_(p) "to"""^(25)C_(r) when each of them has the greatest value possible. (iv) Prove that ""(n-1)C_(3) + ""^(n-1)C_(4) gt""^(n)C_(3) if n> 7 (v) Find r if ""^(15)C_(3r) = ""^(15)C_(r+3 )

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ANSWER :ii. 792. (III) `(143)/(4025)`; (v) r = 3
4.

The solution of the differential equation (dy)/(dx)=(x-2y+1)/(2x-4y) is

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`(X-2y)^(2)+2X=C`
`(x-2y)^(2)+x=c`
`(x-2y)+2x^(2)=c`
`(x-2y)+x^(2)=c`

ANSWER :A
5.

Find the cartesian equation fo the following planes. vecr.(hati+hatj-hatk)=2

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Answer :Replacing `vecr` by `xhati+yhatj+zhatk` we have `(xhati+yhatj+zhatk).(hati+hatj+hatk) = 2` i.e., x+yz=2, which is the CARTESIAN EQUATION of the PLANE
6.

If|z _1 |= 2and(1-i)z_2+(1+i)barz_2= 8sqrt2, then the minimumvalue of|z_1 - z_2| is ______.

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Solution : `|z_(1)| = 2`
Thisimplies that `z_(1)` lies on the circlehaving centre at origin and radius 2.
`(1-i) z_(2) +(1+i) barz_(2) = 8sqrt(2)`
`THEREFORE (1-i)(x_(2) + iy_(2)) +(1+i)(x_(2) -iy_(2)) = 8sqrt(2)`
`rArr x_(2)+y_(2) = 4sqrt(2)`
So, `z_(2)` lies on thestraightline ` + y = 4sqrt(2)`

`|z_(1) -z_(2)|_("min")=` shortest distance betweencircleand straightline
= AB
`= OB - OA`
`= 4- 2=2`
7.

Integrate the rational functions in exercise. (cosx)/((1-sinx)(2sinx))

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ANSWER :`LOG|(2-sinx)/(1-sinx)|+C`
8.

The number of real solutions of the equation : cos^(7)x + sin^(4)x = 1 in the interval [-pi,pi] is :

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0
`PI`
`-pi`
NONE of these.

Answer :A
9.

If |{:(a+ib,c+id),(-c+id,a-ib):}|xx|{:(alpha-ibeta,gamma-idelta),(-gamma-idelta,alpha+ibeta):}|=|{:(A-iB,C-iD),(-C-iD,A+iB):}|, write down the values of A, B, C, (i=sqrt(-1)). Hence show that, the product of two sums, each of four squares, can be expressed as the sum of four squares.

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ANSWER :`A=a ALPHA+b BETA-c GAMMA+d DELTA, B=a beta-b alpha-balpha+c delta+d gamma`,
` C=a gamma+b delta+calpha-d beta, D=a delta-b gamma-b gamma-c beta-d alpha`,
10.

Five dice are tossed. What is the probability that the five numbers shown will be different?

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`(5)/(54)`
`(5)/(18)`
`(5)/(27)`
`(5)/(81)`

Answer :A
11.

IF A be the area bounded by the x-axis and one are of the curve y= acos 3xbetween (0,0) and ((pi)/(6),0)and B be the area bounded by the x-axis and one are of the curve y=acos ^((x)/(4)) between (0,0) and (2pi,0)show that ,A : B =1: 12

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ANSWER :2square UNITS
12.

Using the properties of determinants in Exercise 1 to 6, evaluate |{:(0,xy^2,xz^2),(x^2y,0,yz^2),(x^2z,y^2z,0):}|

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ANSWER :`thereforeD=2x^3y^3z^3`
13.

The value of cos^(2)45^(@)-sin^(2)15^(@) is

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`(SQRT(3))/(2)`
`(sqrt(3))/(4)`
`(sqrt(3)+1)/(2sqrt(2))`
`(sqrt(3)-1)/(2sqrt(2))`

Answer :B
14.

The maximum value of sin x.cos x is ………….

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`(1)/(4)`
`(1)/(2)`
`SQRT(2)`
`2sqrt(2)`

Answer :B
15.

The shortest distance of the lines bar r_1 = 4 hat i -3 hat j - hat k + lambda (2 hat i - 3 hat j + 8 hat k ) is.......

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3
1
2
0

Answer :D
16.

If from any point on the circle x^(2)+y^(2)+3gx+2fy+c=0 tangents are drawn to the circle x^(2)+y^(2)+2gx+2fy+c sin^(2)alpha+(g^(2)+f^(2)) cos^(2)alpha=0,(0 lt alpha lt(pi)/(2)) then the angle between those tangents is

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`(pi)/(4)`
`(pi)/(3)`
`2ALPHA`
`ALPHA`

Answer :C
17.

Solved the following system of linear equations by matrix inversion method.2x+5y=-2, x+2y=-3

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ANSWER :`x=-11, y=4`
18.

Prove that :int_(0)^(oo) log (x+(1)/(x)). (dx)/(1+x^(2)) = pi log_(e) 2

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19.

Two hunters A and B set out to hunt ducks. Each of them hits as often as he misses when shooting at ducks. Hunter A shoots at 50 ducks and hunter B shoots at 51 ducks. The probabilitythat B bags more ducks than A can be expressed as (p)/(q) in its lowest form. Find the value of (p+q).

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ANSWER :3
20.

How many numbers between 6000 and 10000 can be formed using the digits 2, 3, 4, 6, 7, 9 without repetition.

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ANSWER :180
21.

If the angle between the lines having direction ratios (alpha, 3,5) and (2, -1, 2) is (pi)/(4) then alpha is:

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4
3
2
1

Solution :N/A
22.

If [x] denotes the greatest integer le x , then underset( n rarr oo ) ( "Lim") (1)/( n^(4)) ( [1^(3) x ]+ [2^(3) x ] +"....." +[n^(3) x ] )equals

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`X //2`
`x//3`
`x//6`
`x//4`

ANSWER :D
23.

Compute the magnitude of the following vectors : (i) vec(a)=2hati+3hatj+sqrt(3)hatk (ii) vec(b)=3hati-4hatk (iii) vec( c )=hati+hatj-4hatk

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ANSWER :(i) 4 (II) 5 (iii) `3sqrt(2)`
24.

A biased coin with probability of getting head is twice that of tail, is tossed 4 times If a random variable X is number of heads obtained, then expected value ofX is :

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` ( 2 ) /(3 ) `
` (8 ) /(3) `
`2`
` (16 ) /(3) `

Solution :LetX is number of heads OBTAINED
` p = (2)/(3)` probability of GETTING head
`q = (1)/(3)` probability of getting tail.


`E(x)= Sum xi pi`
` = 0 (1)/(3^(4)) + 1XX (8)/(3^(4)) + 2 x(24)/(3^(4)) +4 xx (16)/(3^(4)) = (216)/(81)=(8)/(3)`` E (x)= (8)/(3)` .
25.

If x=8+3sqrt(7)" and "xy=1, then the value of (1)/(x^2)+(1)/(y^2) is

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254
192
292
66

Answer :A
26.

For any two vectorsbar(a)andbar(b) , show that(1+|bara|^(2))(1+|barb|^2)=|1-bar(a).bar(b)|^(2)+|bar(a)+bar(b)+bar(a)xxbar(b)|^(2)

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ANSWER :`(1+|bar(a)|)^(2)+(1+|bar(B)|)^(2)` = LHS.
27.

If veca=hati+lamdahatj+2hatk,vecb=muhati+hatj-hatk are orthogonal and |veca|=|vecb| , then (lamda,mu)=

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`(1/4,7/4)`
`(7/4,1/4)`
`(1/4,9/4)`
`((-1)/4,9/4)`

ANSWER :A
28.

Using the Rolle's theorem, determine the values of x at which the tangent is parallel to the x-axis for the following functions : (i) f(x)=x^(2)-x, x in [0,1] (ii) f(x)=(x^(2)-2x)/(x+2), x in [-1, 6] (iii) f(x)=sqrtx-(x)/(3), x in [0,9]

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ANSWER :`X=(9)/(4)`
29.

2[7^(-1)+3^(-1)7^(-3)+5^(-1)7^(-5)+…]=

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`log_(e )((4)/(3))`
`log_(e )((3)/(4))`
`2LOG((3)/(4))`
`2log((4)/(3))`

ANSWER :A
30.

Transform 12x^(2)+7xy-12y^(2)-17x-31y-7=0 to rectangular through the point (1, -1) inclined at an angle tan^(-1)((4)/(3)) to the original axes.

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ANSWER :XY = 0
31.

State which of the following statements are true (T) or false(F) The line (x-1)/2=(y-1)/2=(z-1)/2 pass though the origin.

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ANSWER :T
32.

Integrate the function (sec^(2)x)/(sqrt(tan^(2)x+4))

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ANSWER :`I=log|THETA+sqrt(theta^(2)+2^(2))|+C`
33.

Differentiate (5x+8)(x^(3)+7x+9) in the way mentioned below : by expanding the product to obtain a single polynomial.

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34.

For all real values of x, the minimum value of (1+x+x^(2))/(1+x+x^(2)) is

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0
1
3
`(1)/(3)`

ANSWER :D
35.

Using calculus prove that log_(3) gt log_(3)5gt log_(4)7.

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36.

Evaluate (2005int_(0)^(1002)dx(sqrt(1002^(2)-x^(2))+sqrt(1003^(2)-x^(2)))+int_(1002)^(1003)sqrt(1003^(32)-x^(2))dx)/(int_(0)^(1)sqrt(1-x^(2))dx)=k, then find the sum of squares of digits of naturalnumber k.

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SOLUTION :N//A
37.

If A_(1),A_(2)….., A_(n) are theverticesof a regularplanepolygonwith n sidesand o isits centre. Thenshowthat Sigma_(n-1)^(i-1) (overset(to)(OA)_(i) xx overset(to)(OA)_(i+1) ) =(1-n)(overset(to)(OA)_(2)xxoverset(to)(OA)_(1))

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<P>

Solution :Since `vec(OA)_(1) , vec(OA)_(2) ,…….vec(OA)_(n)` are llvectors ofsamemagnitudeand anglebetweenany twoconsectivevectorsis samei.e.,`(2pi//n)`
`:. , vec(OA)_(1) xx vec(OA)_(2) = a^(2) sin .(2pi)/(n). P`
where`hat(p) ` isperpendicularto planeof polygon.
Now `OVERSET(n-1)underset(i=1)(Sigma) (vec(OA)_(i) xx vec(OA)_(i+1) ) = overset(n-1)underset(i=1)(Sigma) a^(2). sin.(2pi)/(n).p`
` =(n-1) .a^(2) sin.(2pi)/(n).hat(p)`
`=(n-1) [vec(OA)_(1) xx vec(OA)_(2)]`
`=(1-n)[vec(OA)_(2) xx vec(OA)_(1)] =RHS`
38.

If f(x)=unerset(x^2)overset(x^(2+1))e^(-t^2) dt then f(x) increases on

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`(-2,2)`
`(0,OO)`
`(-oo,0)`
NONE of these

ANSWER :C
39.

Differentiate w.r.t.x the function. cot^(-1)[(sqrt(1+sin x)+sqrt(1-sin x))/(sqrt(1+sin x)-sqrt(1-sin x))],0 lt x lt (pi)/(2).

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ANSWER :`(1)/(2)`
40.

A person plays a game of tossing a coin thrice. For each head, he is given Rs 2 by the organiser of the game and for each tail, he has to give Rs 1.50 to the organiser. Let X denote the amount gained or lost by the person. Show that X is a random variable and exhibit it as a function on the sample space of the experiment.

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ANSWER :{-1, 2.50, -4.50, 6}
41.

Let I = int_1^2 (dx)/(sqrt(1 + x^2)), J = int_1^2 (dx)/(x), then

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`I = J`
`I LT J`
`I GT J`
NONE of these

ANSWER :B
42.

Let f(x) = {{:(int_(0)^(x){5+|1-t|}dt",","if",x gt 2),(5x + 1",","if",x le 2):} Test f(x) for continuity and differentiability for all real x.

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ANSWER :X = 2
43.

Express the following matrices as the sum of a symmetric and a skew symmetric matrix : (i) [{:(3,5),(1,-1):}](ii)[{:(6,-2,2),(-2,3,-1),(2,-1,3):}](iii)[{:(3,3,-1),(-2,-2,1),(-4,-5,2):}](iv)[{:(1,5),(-1,2):}]

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Answer :(i) `thereforeA=[{:(3,3),(3,-1):}]+[{:(0,2),(-2,0):}]`
(II) `=[{:(6,-2,2),(-2,3,-1),(2,-1,3):}]+[{:(0,0,0),(0,0,0),(0,0,0):}]`
(iii) `=[{:(3,(1)/(2),-(5)/(2)),((1)/(2),-2,-2),(-(5)/(2),-2,2):}]+[{:(0,(5)/(2),(3)/(2)),(-(5)/(2),0,3),(-(3)/(2),-3,0):}]`
(iv) `=[{:(1,2),(2,2):}]+[{:(0,3),(-3,0):}]`
44.

log_(4)2-log_(8)2+log_(16)2-....=

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`E^(2)`
`log_(e )2+1`
`log_(e )3-2`
`1-log_(e) 2`

ANSWER :D
45.

For real numbers x and y, define xRY if and only if x - y + sqrt(2) is an irrational number.Then the relation R is

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Reflexive
Symmetric
Transitie
NONE of these

Answer :A
46.

Find derivatives of the following functions. 1/(x^3 + sinx)^2

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SOLUTION :`y = 1/{(x^3 + SINX)^2} = (x^3 + sinx)^(-2)
dy/dx = -2(x^3 + sinx)^(-3)XX d/dx (x^3 + sinx)
= -2/{(x^2 + sinx)^3}.(3x^2 + cosx)
-{2(3x^2 + cosx)}/{(x^3 + sinx)^3}`
47.

Sum of the squares of the first 3 terms of the given series is

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1100
660
799
1000

Solution :`T_(1)^(2),T_(2)^(2),T_(3)^(2)=8^(2)+14^(2)+20^(2)=64+196+400=660`
48.

Let angleA=23^(@), angleB=75^(@) and angleC=82^(@) be the angles of DeltaABC. The incircle of DeltaABC touches the sides BC, CA, AB at points D, E, F respectively. Let r', r_(1)^(') respectively be the inradius, exradius opposite to vertex D of DeltaDEF and r be inradiusof DeltaABC, then Q.(r_(1)^('))/(r )=

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`"sin"(A)/(2)+"sin"(B)/(2)+"sin"(C )/(2)-1`
`1-"sin"(A)/(2)+"sin"(B)/(2)+"sin"(C )/(2)`
`"cos"(A)/(2)+"cos"(B)/(2)+"cos"(C )/(2)-1`
`1-"cos"(A)/(2)+"cos"(B)/(2)+"cos"(C )/(2)`

ANSWER :B
49.

If A is a matrix of order 3, such that A(adj A) = 10 I, then find |adj A| =

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1
10
100
10I

Answer :C
50.

Let angleA=23^(@), angleB=75^(@) and angleC=82^(@) be the angles of DeltaABC. The incircle of DeltaABC touches the sides BC, CA, AB at points D, E, F respectively. Let r', r_(1)^(') respectively be the inradius, exradius opposite to vertex D of DeltaDEF and r be inradiusof DeltaABC, then Q.(r')/(r)=

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`"sin"(A)/(2)+"sin"(B)/(2)+"sin"(C )/(2)-1`
`1-"sin"(A)/(2)+"sin"(B)/(2)+"sin"(C )/(2)`
`"COS"(A)/(2)+"cos"(B)/(2)+"cos"(C )/(2)-1`
`1-"cos"(A)/(2)+"cos"(B)/(2)+"cos"(C )/(2)`

Answer :A