Probability(Quantitative Aptitude ) Questions and answers for exam Preparation

Quantitative Aptitude

PROBABILITY MCQs

Probability, Probability I

Total Questions : 775 | Page 8 of 78 pages

Question 71. In a cricket match, a batsman hit a boundary 6 times (out of 30 balls). Find the probability that next ball he plays is not a boundary.

Discuss Question

Answer: Option D. -> 0.8
:
D
Total number of balls played = 30
Number of balls in which the batsman hit a boundary= 6
Number of balls in which he didnot hit a boundary
= 30 – 6
= 24

∴ Probability of not hitting a boundary = \frac{Number of balls in which he does not hit a boundary}{Total number of balls played} = \frac{24}{30} = 0.8

Question 72. Parts exiting an assembly line are inspected and categorized as good or bad (defective). In a batch of 100 parts, 8 were found to be defective.
What is the probability that a part drawn at random is defective?

0.2
0.02
0.08
0.8

Discuss Question

Answer: Option C. -> 0.08
:
C
Number of parts exiting an assembly line which are bad(defective) = 8
Total number of parts passing the assembly line = 100
Probability of part being defective

= \frac{Number of defective parts}{Total number of parts}

Probability of a part being defective

= \frac{8}{100} = 0.08

Question 73. A die is thrown 1000 times with the frequencies for the outcomes 1, 2, 3, 4, 5 and 6 as given in the following table:

\begin{matrix} Outcome & Frequency 1 & 165 2 & 175 3 & 180 4 & 150 5 & 145 6 & 185 \end{matrix}

What is the probability of getting 2 or 4?

0.515
0.245
0.325
0.455

Discuss Question

Answer: Option C. -> 0.325
:
C
Number of times 2 or 4 appears when a die was rolled = 175 + 150 = 325
Total number of times a die is thrown = 1000
Probability of getting a 2 or a 4

= \frac{number of times 2 or 4 appears}{total number of times a die is thrown}

\Rightarrow Probability = \frac{325}{1000} = 0.325

Question 74. Out of 50 students in a class taking a test, 35 of them passed whereas the other 15 failed. What is the probability that a student drawn at random passed the exam?

0.15
0.3
0.35
0.7

Discuss Question

Answer: Option D. -> 0.7
:
D
Total number of students in a class = 50
Number of students who passed an examination = 35
Probability that a student passed the exam =

\frac{Number of students who passed an examinatio}{Total number of students in a class}

Probability that a student passed the exam =

\frac{35}{50} = 0.7

Question 75. Two dice are thrown simultaneously. Find the probability of getting a sum of 12.

Discuss Question

Answer: Option D. -> 136
:
D
Total number of outcomes when two dice are thrown =
(1,1), (1,2), (1,3), (1,4), (1,5), (1,6), (2,1), (2,2), (2,3), (2,4), (2,5), (2,6), (3,1), (3,2), (3,3), (3,4), (3,5), (3,6), (4,1), (4,2), (4,3), (4,4), (4,5), (4,6), (5,1), (5,2), (5,3), (5,4), (5,5), (5,6), (6,1), (6,2), (6,3), (6,4), (6,5), (6,6) = 36.
Sum of 12 = (6,6)
Therefore, Probability of getting a sum of 12 =

\frac{1}{36}

Question 76. Two kids Goutham and Pavani are fighting for coins. Finally, Goutham won and stole a coin from Pavani's pocket which has four different coins ( a 1 rupee coin, a 2 rupee coin, a 5 rupee coin, a 10 rupee coin). What are the total number of possible outcomes when Goutham tried to steal a coin?

Discuss Question

Answer: Option A. -> 4
:
A
As there are four different coins in Pavani's pocket, so there are 4 possible ways in which Goutham can steal a coin i.e. 1 rupee coin, 2 rupee coin, 5 rupee coin, 10 rupee coin. Therefore a total number of possible outcomes are 4.

Question 77. Which of the following is not the outcome when you throw an unbiased die?

Getting a face of 1
Getting a face of 2
A multiple of 7
A multiple of 2

Discuss Question

Answer: Option C. -> A multiple of 7
:
C
When you throw an unbiased die, the outcomes are1, 2, 3, 4, 5 and 6 and none of them are multiple of 7.

Question 78. If we roll a die, there are total six possible outcomes (1,2,3,4,5,6). What is the probability of getting 2?

Discuss Question

Answer: Option B. -> 16
:
B
Suppose a dieis rolled, the possible outcomes are1, 2, 3, 4, 5, 6. Each number appearing on the face of adiedoes not affect the other numbers.Each number has aprobability of

\frac{1}{6}

to occur when a die is rolled. It does not depend on the number that it shows.
For instance, the probability that we roll a die and 2 comes is

\frac{1}{6}

, since there is only single 2 on the cube.

Question 79. Last week, it rained on 5 days out of 7 days. The probability that if we pick a random day from the week, it will be a rainy day is

Discuss Question

Answer: Option A. -> 57
:
A
Given, it had rained 5 out of 7 days.
i.e., Number of rainy days = 5
Total number ofdays = 7
Then,

Probability = \frac{Number of rainy days}{Total number of days} = \frac{5}{7}

Question 80. It is 82% likely that India will win the match means that, ___.

there is 100% chance that India will win.
there is 18% chance for India to lose the match. So India will definitely not win.
there is 82% chance that India will win. So India will certainly win.
there is 82% chance that India will win but we cannot say that India will definitely win.

Discuss Question

Answer: Option D. -> there is 82% chance that India will win but we cannot say that India will definitely win.
:
D
It is 82% likely that India will win the match means that there is 82% chance that India is winning the match. There is still 18% uncertainty that India will not win. In terms of probability, the probability of India winning will be 0.82. So India may or may not win. Therefore, we cannot say that India will definitely win.