During business hours, the number of calls passing through a particular cellular relay system averages 5 per minute.

(a)

Find the probability that no call will pass through the relay system during a given minute.

$\displaystyle P(X=0)=p(0)=\frac{5^0}{0!}e^{-5}=.0067$

(b)

Find the probability that no call will pass through the relay system during a given 2 minute period.

$\displaystyle [P(X=0)]^2=[p(0)]^2=\frac{5^0}{0!}e^{-10}=.0000454$

Not so sure about this one.

(c)

Find the probability that 3 calls will pass through the relay system during a given minute.

$\displaystyle P(X=3)=p(3)=\frac{5^3}{3!}e^{-5}=.1404$

Correct?