b$)$ A survey conducted in a country revealed that $70\%$ of the IT businesses generated a profit within $5$

years of start. A sample of $15$ IT businesses were taken. Find the probability that exactly $8$ will generate

a profit in the first year.

c$)$ A company conducted tests on charging times of various smart phones. It is reported that a phone will

work before it needs charging is normally distributed with a mean of $80$ hours and a standard deviation of

$13$ hours. Find the probability that a randomly selected smart phone will need charging after $120$ hours.