Probability Quiz Set 016

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Question 1

A box contains 41 red balls and an unknown number of blue balls. If the probability of drawing a blue ball is 3 times the probability of drawing a red ball, then how many blue balls are there in the box?

 A

123.

 B

128.

 C

118.

 D

133.

Soln.
Ans: a

Let the number of blue balls be x. Chances of drawing a blue ball are $x/{x + 41}$ = 3 × $41/{x + 41}$, which gives x = 3 × 41 = 123.


Question 2

A bag contains 2 Red, 6 Blue and 3 Green marbles. What is the probability of drawing a Red marble if 2 marbles are drawn out randomly?

 A

${19/55}$.

 B

$3/11$.

 C

$20/55$.

 D

$24/55$.

Soln.
Ans: a

Total number of marbles is 11. Combinations of 2 marbles that are possible = 11C2 = ${11 × 10}/2$ = 55. If one of the two balls is red, then red + red is one possibility, and 2 × (6 + 3) are the other possibilities. So total favorable outcomes = 1 + 2 × 9 = 19, and the probability is 19/55 = ${19/55}$.


Question 3

12 bowls are lying inverted on a table. 8 of them contain marbles, but 4 of them are empty. What is the probability of getting a marble if one of the bowls is opened randomly?

 A

${2/3}$.

 B

$9/12$.

 C

$4/3$.

 D

$7/3$.

Soln.
Ans: a

Chances favoring a marble are 8, whereas the total chances are 12. The probability is 8/12 = ${2/3}$.


Question 4

Karmjeet and Sham are friends. What is the probability that both will have different birthdays, ignoring a leap year?

 A

${364/365}$.

 B

$21/365$.

 C

$365/365$.

 D

$369/365$.

Soln.
Ans: a

The birthday of second friend has 365 outcomes. If it is not to match the birthday of the first friend, the number of favorable outcomes is 365 - 1 = 364. So probability is 364/365.


Question 5

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.


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Creative Commons License
This Blog Post/Article "Probability Quiz Set 016" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2019-08-18.

Posted by Parveen(Hoven),
Aptitude Trainer


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