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Probability ( 6 to 10 ):
APTITUDE QUESTIONS (PROBABILITY):
6. 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)
E) None of these
View Answer
Answer: option (C)
Explanation:
In two throws of a dice, n(S) = (6 * 6) = 36
Let E = event of getting a sum 9 = {(3,6), (4,5), (5,4), (6,3)}
∴ P(E) = (n(E)/n(S)) = (4/36) = (1/9)
7. In a simultaneous throw of two dice, what is the probability of getting a doublet?
A) (1/6)
B) (1/4)
C) (2/3)
D) (3/7)
E) None of these
View Answer
Answer: option (A)
Explanation:
In a simultaneous throw of two dice, n(S) = (6 * 6) = 36
Let E = event of getting a doublet = {(1,1) , (2,2) , (3,3) ,(4,4), (5,5), (6,6)}
∴ P(E) = (n(E)/n(S)) = (6/36) = (1/6)
8. In a simultaneous throw of two dice, what is the probability of getting a total of 10 or 11?
A) (1/4)
B) (1/6)
C) (7/12)
D) (5/36)
E) None of these
View Answer
Answer: option (D)
Explanation:
In a simultaneous throw of two dice, we have n(S) = (6 * 6) = 36
Let E = event of getting a total of 10 or 11 = {(4,6) , (5,5) , (6,4) ,(5,6), (6,5)}
∴ P(E) = (n(E)/n(S)) = (5/36)
9. Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn bears a number which is a multiple of 3?
A) (3/10)
B) (2/20)
C) (2/5)
D) (1/2)
E) None of these
View Answer
Answer: option (A)
Explanation:
Here, S = {1, 2, 3, 4, ….., 19, 20}
Let E = event of getting a multiple of 3 = {3, 6, 9, 12, 15, 18}
∴ P(E) = (n(E)/n(S)) = (6/20) = (3/10)
10. 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)
E) None of these
View Answer
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)/n(S)) = (9/20)