First slide
Random variable and probability distribution
Question

A pair of fair dice is thrown independently three times the probability of getting a score of 9 exactly twice is

Moderate
Solution

 In a single throw 9 occurs as (3,6),(4,5),(5,4),(6,3)

 The probability p=436=19

 The probability of getting 9 twice is =3C2p2(1-p)=8243

Get Instant Solutions
When in doubt download our app. Now available Google Play Store- Doubts App
Download Now
Doubts App