# Probability Quiz Set 017

### Question 1

A class has 7 boys and 4 girls. What is the probability of choosing 1 boy and 2 girls?

A

\${14/55}\$.

B

\$8/11\$.

C

\$15/55\$.

D

\$19/55\$.

Soln.
Ans: a

Three students have to be picked. Total number of ways = 11C3 = \${11 × 10 × 9}/{3 × 2 × 1} = \$165. Number of ways of picking 1 boy and 2 girls = 7C1 × 4C2 = 42. So probability = \$42/165\$ = \${14/55}\$.

### Question 2

Which of these cannot be a probability of an event?

A

-1.5.

B

2/3.

C

15%

D

0.7.

Soln.
Ans: a

The probability of an event is a number from 0 to +1 only. 0 means no probability and +1 means certainty.

### Question 3

Two players, A and B, play a game. It is known that probability of A's victory is 0.58. What is the probability of B's victory?

A

0.42.

B

0.58.

C

0.5.

D

0.25.

Soln.
Ans: a

One of the two is going to win. Probability of A's defeat is 1 - 0.58 = 0.42, which is the probability of B's victory.

### Question 4

Two fair dice are tossed simultaneously. What is the probability that the total score is a prime number?

A

5/12.

B

3/5.

C

1/6.

D

5/36.

Soln.
Ans: a

Out of a total of 6 × 6 = 36 outcomes, the favorable ones are: (1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4, 3), (5, 2), (5, 6), (6, 1), (6, 5). So total favorable are: 15. Probability = 15/36 = 5/12.

### Question 5

48 defective pens are accidentally mixed with 56 good ones. It is not possible to just look at a pen and tell whether it is defective or not. One pen is taken out at random. What is the probability that it is a defective pen?

A

\${6/13}\$.

B

\$50/104\$.

C

\$7/104\$.

D

\$11/104\$.

Soln.
Ans: a

Out of the total number of pens = 104, the chances favoring defective pen are 48. So the probability is 48/104 = \${6/13}\$.

This Blog Post/Article "Probability Quiz Set 017" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-04-07.

Posted by Parveen(Hoven),
Aptitude Trainer