Question

The probability that class ends early any day is .7. What is the probability class ends early more than 9 out of 15 days?

Answer 1

The probability that class ends early any day is 0.7

Hence p=0.7

And we taking sample of any 15 days

Hence n=15

class ends early any day is independent on each another day.

Therefore,

This is binomial distribution

Here X~ B(n=15 ,p=0.7)

So we know in binomial Distribution

probability class ends early more than 9 out of 15 days is,

the probability class ends early more than 9 out of 15 days is 0.7216