On average, ten customers enter a shop within an hourfollowing a Poisson Distribution.

$P(r)=\frac{{}^r}{r!}{e}^{-},$ where $=np$

determine the probability that

$($a$)$ exactly $5$ customers enter the shop.

$($b$)$ less than $5$ customers enter the shop.

$($c$)$ more than $5$ customers enter the shop.

Round the answer to $4$ decimals places.