Question

Two dice are rolled. the probability of getting a sum of at least 9 is

Answer 1

the total probability of gettting a sum of at least is 9 is 15/36

Answer 2

The probability of getting a sum of at least 9 is 5/18

Step-by-step explanation:

Given:

Two dice are rolled

To find:

probability of getting a sum of at least 9

Solution:

When two dices are rolled

S={(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)}

∴ n(S) =36

Let A be the event of getting a sum of at least 9, i.e. 9 or more than 9

A={(3,6),(4,5),(4,6),(5,4),(5,5),(5,6),(6,3),(6,4),(6,5),(6,6)}

∴ n(A) =10

The probability of the event A= P(A)= n(A)/n(S)

P(A)= 10/36

P(A)= 5/18

The probability of getting a sum of at least 9 is 5/18.

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