# Probability ( 6 to 10 )

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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

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

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

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

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

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)