Roo Fitness will install $3$ new trapezoidal gel$-$resistance toners, or "trappies," which are

the latest exercise gadget specifically designed to contour upper back muscles. Clients

who want to use these machines arrive at the rate of $85$ per hour. The coefficient of

variation of the interarrival times is $3.$ If all three machines are busy, Roo Fitness clients

use other pieces of equipment, waiting for one of the "trappies" to become available.

The trappy experience is intense$120$ seconds of explosive exercise intensity. The

standard deviation of the usage times $($measured in seconds$)$ is quite small$$only $30.$

$($a$)$ On average, how long does a Roo Fitness client wait before using a trappy?

$($b$)$ On average, how many Roo Fitness clients are waiting to use a trappy?

$($c$)$ On average, how many Roo Fitness clients are using a trappy?