13
Q:

An urn contains 4 white 6 black and 8 red balls . If 3 balls are drawn one by one without replacement, find the probability of getting all white balls.

A) 5/204 B) 1/204
C) 13/204 D) None of these

Answer:   B) 1/204



Explanation:

Let A, B, C be the events of getting a white ball in first, second and third draw respectively, then 

Required probability = 

Now, P(A) = Probability of drawing a white ball in first draw = 4/18 = 2/9

When  a white ball is drawn in the first draw there are 17 balls left in the urn, out of which 3 are white

Since the ball drawn is not replaced, therefore after drawing a white ball in the second draw there are 16 balls left in the urn, out of which 2 are white.

Hence the required probability = 

Q:

Two dice are rolled simultaneously. Find the probability of getting the sum of numbers on the on the two faces divisible by 3 or 4?

A) 3/7 B) 7/11
C) 5/9 D) 6/13
 
Answer & Explanation Answer: C) 5/9

Explanation:

Here n(S) = 6 x 6 = 36

E={(1,2),(1,5),(2,1),(2,4),(3,3),(3,6),(4,2),(4,5),(5,1),(5,4),(6,3) ,(6,6),(1,3),(2,2),(2,6),(3,1),(3,5), (4,4),(5,3),(6,2)}

=> n(E)=20

Required Probability n(P) = n(E)/n(S) = 20/36 = 5/9.

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10 75
Q:

A person starting with 64 rupees and making 6 bets, wins three times and loses three times, the wins and loses occurring in random order. The chance for a win is equal to the chance for a loss. If each wager is for half the money remaining at the time of the bet, then the final result is:

A) A gain of Rs. 27 B) A loss of Rs. 37
C) A loss of Rs. 27 D) A gain of Rs. 37
 
Answer & Explanation Answer: B) A loss of Rs. 37

Explanation:

As the win leads to multiplying the amount by 1.5 and loss leads to multiplying the amount by 0.5, we will multiply the initial amount by 1.5 thrice and by 0.5 thrice (in any order).

The overall resultant will remain same.

So final amount with the person will be (in all cases):

64(1.5)(1.5)(1.5)(0.5)(0.5)(0.5)= Rs. 27

Hence the final result is: 

64 − 27 37

A loss of Rs.37

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8 120
Q:

A card is drawn from a pack of 52 cards. The probability of getting a queen of the club or a king of the heart is?

A) 1/26 B) 1/13
C) 2/13 D) 1/52
 
Answer & Explanation Answer: A) 1/26

Explanation:

Here in this pack of cards, n(S) = 52

Let E = event of getting a queen of the club or a king of the heart

Then, n(E) = 2

P(E) = n(E)/n(S) = 2/52 = 1/26

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7 205
Q:

A room contains 3 brown, 5 black and 4 white chairs. Two chairs are picked and are put in the lawn. What is the probability that none of the chairs picked is white ?

A) 14/33 B) 14/55
C) 12/55 D) 13/33
 
Answer & Explanation Answer: A) 14/33

Explanation:

Total number of chairs = (3 + 5 + 4) = 12.

Let S be the sample space.

Then, n(s)= Number of ways of picking 2 chairs out of 12

12×11/2×66

Let n(E) = number of events of selecting 2 chairs for selecting no white chairs.

=> 8C8×7/2×28

Therefore required probability = 28/66 = 14/33.

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7 578
Q:

The probability that a bowler bowled a ball from a point will hit by the batsman is ¼. Three such balls are bowled simultaneously towards the batsman from that very point. What is the probability that the batsman will hit the ball ?

A) 37/64 B) 27/56
C) 11/13 D) 9/8
 
Answer & Explanation Answer: A) 37/64

Explanation:

Probability of not hitting the ball = 1- 1/4 =IBPS RRB Clerk Level Quiz : Quantitative Aptitude | 11 -09 - 17
Then, the probability that the batsman will hit the ball =IBPS RRB Clerk Level Quiz : Quantitative Aptitude | 11 -09 - 17

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9 537