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Q:

A number X is chosen at random from the numbers -3, -2, -1, 0, 1, 2, 3. What is the probability that |X|<2

A) 3/7 B) 3/4
C) 4/5 D) 5/7
 
Answer & Explanation Answer: A) 3/7

Explanation:

X can take 7 values.
To get |X|+2) take X={−1,0,1}

=> P(|X|<2) = Favourable CasesTotal Cases = 3/7

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Filed Under: Probability

Q:

A man sells Rs.5000, 12 % stock at 156 and uinvests the proceeds parity in 8 % stock at 90 and 9 % stock at 108. He hereby increases his income by Rs. 70. How much of the proceeds were invested in each stock?

A) 4000 B) 4200
C) 4002 D) 4020
 
Answer & Explanation Answer: B) 4200

Explanation:

S.P of Rs. 5000 stock = Rs.156100*5000= Rs. 7800. 

 

Income from this stock = Rs.12100*5000 = Rs. 600.  

 

Let investment in 8 % stock be x and that in 9 % stock = (7800 - x).

 

Therefore,  

 

x*890+7800-x*9108=600+70  

 

4x45+7800-x12=670x=3600 

 

Therefore,  Money invested in 8 % stock at 90 = Rs. 3600.

 

Money invested in 9 % at 108 = Rs. (7800-3600) = Rs. 4200.

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Filed Under: Stocks and Shares

Q:

If (i) M is brother of N; (ii) B is brother of N; and (iii) M is brother of D, then which of the following statements is definitely true ?

A) N is brother of B B) N is brother of D
C) M is brother of B D) D is brother of M
 
Answer & Explanation Answer: C) M is brother of B

Explanation:

M is the brother of N and B is the brother of N. 

So, M is the brother of B

 

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Filed Under: Blood Relations

Q:

Two cards are drawn at random from a pack of 52 cards.what is the probability that either both are black or both are queen?

A) 52/221 B) 55/190
C) 55/221 D) 19/221
 
Answer & Explanation Answer: C) 55/221

Explanation:

We have n(s) =52C2 52 = 52*51/2*1= 1326. 

Let A = event of getting both black cards 

     B = event of getting both queens 

A∩B = event of getting queen of black cards 

n(A) = 52*512*1 = 26C2 = 325, n(B)= 26*252*1= 4*3/2*1= 6  and  n(A∩B) = 4C2 = 1 

P(A) = n(A)/n(S) = 325/1326;

P(B) = n(B)/n(S) = 6/1326 and 

P(A∩B) = n(A∩B)/n(S) = 1/1326 

P(A∪B) = P(A) + P(B) - P(A∩B) = (325+6-1) / 1326 = 330/1326 = 55/221

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Filed Under: Probability

Q:

A bag contains 6 white and 4 black balls .2 balls are drawn at random. Find the probability that they are of same colour.

A) 1/2 B) 7/15
C) 8/15 D) 1/9
 
Answer & Explanation Answer: B) 7/15

Explanation:

Let S be the sample space

 

Then n(S) = no of ways of drawing 2 balls out of (6+4) =10C2 10 =10*92*1 =45

 

Let E = event of getting both balls of same colour

 

Then,n(E) = no of ways (2 balls out of six) or (2 balls out of 4)

 

                =6C2+4C2 = 6*52*1+4*32*1= 15+6 = 21

 

Therefore, P(E) = n(E)/n(S) = 21/45 = 7/15

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Q:

A family consists of six members P, Q, R, X, Y and Z. Q is the son of R but R is not mother of Q. P and R are a married couple. Y is the brother of R. X is the daughter of P. Z is the brother of P. Which is a pair of brothers ? 

A) P and X B) P and Z
C) Q and X D) R and Y
 
Answer & Explanation Answer: D) R and Y

Explanation:

Q is the son of R but R is not the mother. So, R is the Father of Q. P is married to R 

So, P is the wife of R and the mother of Q, X is the daughter of P and hence of R and so she is the Sister of Q, Y is the brother of R and Z is the brother of P. 

Clearly. Y is brother of R who is a male. So, Y and R are a pair of brothers  

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Filed Under: Blood Relations

Q:

Find the probability that one ball is white when two balls are drawn at random from a basket that contains 9 red, 7 white and 4 black balls.

A) 18/95 B) 18/190
C) 1/2 D) 91/190
 
Answer & Explanation Answer: D) 91/190

Explanation:

Total number of elementary events = 20C2 ways =190

 

There are 7 white balls out of which one white can be drawn in 7C1 ways and one ball from remaining 13 balls can be drawn in 13C1 ways.

 

So,favourable events = 7C1*13C1

 

Therfore,required probability = (7C1*13C1)/20C2=91/90

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Q:

There are six persons A. B, C, D, E and F. C is the sister of F. B is the brother of E's husband. D is the father of A and grandfather of F. There are two fathers, three brothers and a mother in the group. Who is the mother ?

A) A B) B
C) C D) E
 
Answer & Explanation Answer: D) E

Explanation:

D is father of A and grandfather of F. So, A is father of F. 

Thus. D and A are the two fathers. C is the sister of F So. C is the daughter of A. 

Since there is only one mother, it is evident that E is the wife of A and hence the mother of C and F. 

So, B is brother of A There are three brothers. So. F is the brother of C. 

 Clearly, A is E's Husband.

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Filed Under: Blood Relations