Answer
a) ..70
b) .11
Work Step by Step
a. We find:
$\mu=np=(64)(.8)=51.2$
$ \sigma=\sqrt{npq}=\sqrt{(64)(.8)(.2)}=3.2$
Thus, we find z:
$z=\frac{49.5-51.2}{3.2}=-.53$
Thus, using the table of z-scores, we find that this corresponds to a probability of $1-.30=.70$
b. We must find the second z-score:
$z=\frac{50.5-51.2}{3.2}=-.22$
Thus, using the table of z-scores, we find that this corresponds to a probability of $.41-.3=.11$
