Problem $4$:

Suppose a Cellular Service Provider has a total of $84$ channels. Suppose each user contributes $0\mathrm{.}1$ Erlangs of traffic.

$($a$)$ What is the maximum number of users in one cell that can be supported with a $0\mathrm{.}01$ probability of blocking if $4$cell clusters are used?

$($b$)$ What is the maximum number of users in one cell that can be supported with a $0\mathrm{.}01$ probability of blocking if $7-$ cell clusters are used?