Chapter 15.8, Problem 21P

As in Examples 1 and 2, use (a) the binomial distribution; (b) the corresponding normal approximation, to find the probabilities of each of the following:

Verify equations ( 8.6 ). Hints: In $F(x)$, let $u=(t-\mu )/\sigma$; note that $dt=\sigma du$.

What is $u$ when $t=-\infty ?$ When $t=x?$ Remember that by definition $z=(x-\mu )/\sigma$.