Using these givens to answer the question that follows: Arrival rate: $1\mathrm{.}2$ calls per minute, Service rate: $2\mathrm{.}1$ calls per minute. In a single$-$server model what is the probability of $3$ customers in the system?

$0\mathrm{.}265$

$0\mathrm{.}080$

$0\mathrm{.}402$

$0\mathrm{.}749$

$0\mathrm{.}954$

$0\mathrm{.}305$

$0\mathrm{.}375$

$0\mathrm{.}125$

$0\mathrm{.}593$

$0\mathrm{.}850$