Aptitude - Probability

Why Aptitude Probability?

In this section you can learn and practice Aptitude Questions based on "Probability" and improve your skills in order to face the interview, competitive examination and various entrance test (CAT, GATE, GRE, MAT, Bank Exam, Railway Exam etc.) with full confidence.

Where can I get Aptitude Probability questions and answers with explanation?

IndiaBIX provides you lots of fully solved Aptitude (Probability) questions and answers with Explanation. Solved examples with detailed answer description, explanation are given and it would be easy to understand. All students, freshers can download Aptitude Probability quiz questions with answers as PDF files and eBooks.

Where can I get Aptitude Probability Interview Questions and Answers (objective type, multiple choice)?

Here you can find objective type Aptitude Probability questions and answers for interview and entrance examination. Multiple choice and true or false type questions are also provided.

How to solve Aptitude Probability problems?

You can easily solve all kind of Aptitude questions based on Probability by practicing the objective type exercises given below, also get shortcut methods to solve Aptitude Probability problems.

Exercise :: Probability - General Questions

1. 

Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

A.
1
2
B.
2
5
C.
8
15
D.
9
20

Answer: Option D

Explanation:

Here, S = {1, 2, 3, 4, ...., 19, 20}.

Let E = event of getting a multiple of 3 or 5 = {3, 6 , 9, 12, 15, 18, 5, 10, 20}.

P(E) = n(E) = 9 .
n(S) 20


2. 

A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

A.
10
21
B.
11
21
C.
2
7
D.
5
7

Answer: Option A

Explanation:

Total number of balls = (2 + 3 + 2) = 7.

Let S be the sample space.

Then, n(S) = Number of ways of drawing 2 balls out of 7
= 7C2 `
= (7 x 6)
(2 x 1)
= 21.

Let E = Event of drawing 2 balls, none of which is blue.

n(E) = Number of ways of drawing 2 balls out of (2 + 3) balls.
= 5C2
= (5 x 4)
(2 x 1)
= 10.

P(E) = n(E) = 10 .
n(S) 21


3. 

In a box, there are 8 red, 7 blue and 6 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green?

A.
1
3
B.
3
4
C.
7
19
D.
8
21
E.
9
21

Answer: Option A

Explanation:

Total number of balls = (8 + 7 + 6) = 21.

Let E = event that the ball drawn is neither red nor green
= event that the ball drawn is blue.

n(E) = 7.

P(E) = n(E) = 7 = 1 .
n(S) 21 3


4. 

What is the probability of getting a sum 9 from two throws of a dice?

A.
1
6
B.
1
8
C.
1
9
D.
1
12

Answer: Option C

Explanation:

In two throws of a dice, n(S) = (6 x 6) = 36.

Let E = event of getting a sum ={(3, 6), (4, 5), (5, 4), (6, 3)}.

P(E) = n(E) = 4 = 1 .
n(S) 36 9


5. 

Three unbiased coins are tossed. What is the probability of getting at most two heads?

A.
3
4
B.
1
4
C.
3
8
D.
7
8

Answer: Option D

Explanation:

Here S = {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH}

Let E = event of getting at most two heads.

Then E = {TTT, TTH, THT, HTT, THH, HTH, HHT}.

P(E) = n(E) = 7 .
n(S) 8





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