Answer
a)5
b)5
Work Step by Step
a) The expected number of trials to obtain the first success is:
$E(x)=\frac{1}{p}=\frac{1}{0.2}=5$
b) Given that the trials are independent,after the eighth success occurs, the expected number of trials to obtain the ninth success is also $E(x)=\frac{1}{p}=\frac{1}{0.2}=5$
