Answer
$P(8)=0.101$
On about 101 of every 1000 days, there will be exactly 8 calls between 3:10 p.m. and 3:15 p.m.
Work Step by Step
$P(8)=\frac{(2.1\times5)^{8}}{8!}e^{-2.1\times5}=\frac{(10.5)^{8}}{8\times7\times6\times5\times4\times3\times2\times1}e^{-10.5}=0.101$
