Probability Aptitude Test Paper 1
1) What is the probability of getting an even number when a dice is rolled?
- 1/5
- 1/2
- 1/3
- 1/4
Answer: B
Explanation:
The sample space when a dice is rolled, S = (1, 2, 3, 4, 5 and 6)
So, n (S) = 6
E is the event of getting an even number.
So, n (E) = 3
So, the probability of getting an even number P (E) =
=
= 3/6 = 1/2
2) What is the probability of getting two tails when two coins are tossed?
- 1/3
- 1/6
- 1/2
- 1/4
Answer: D
Explanation:
The sample space when two coins are tossed = (H, H), (H, T), (T, H), (T, T)
So, n(S) = 4
The event “E” of getting two tails (T, T) = 1
So, n(E) = 1
So, the probability of getting two tails, P (E) =
= = 1/4
3) The tickets numbered from 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket has a number which is a multiple of 3 or 5?
- 9/20
- 9/24
- 9/27
- 9/30
Answer: A
Explanation:
The sample space, S= (1, 2, 3, 4, 5 …18, 19, 20) or n(S) = 20
The event “E” of getting a multiple of 3 or 5 = (3, 6, 9, 12, 15, 18, 5, 10, 20) or n (E) = 9
So, the probability of getting multiple of 3 or 5, P (E) = = 9/20
4) A box contains 2 red, 3 green, and 2 blue balls. What is the probability that none of the balls drawn is blue?
- 10/25
- 10/21
- 10/31
- 10/21
Answer: B
Explanation:
Total number of balls = (2+3+2) = 7
Let S be the sample space.
Then, n (S) = the total number of ways of drawing two balls out of 7:
= 7C2
Let E is the 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) In a bag, there are 8 red, 7 yellow and 6 green balls. If one ball is picked up at random, what is the probability that it is neither red nor green?
- 1/4
- 1/2
- 1/5
- 1/3
Answer: D
Explanation:
Total number of balls or sample space = 8 + 7+ 6 = 21
So, n(S) = 21
Let E is the event that ball drawn is neither red nor green or event that the ball drawn is yellow. There are 7 yellow balls:
So, n (E) = 7
Probability Aptitude Test Paper 2
Probability Aptitude Test Paper 3