Little's Law $($Waiting$-$line problem$).$ Safety regulations require that the time between airplane takeoffs $($on the same runway$)$ will be at least $2$ minutes. When taking off, the run time of an airplane on the runway is $45$ seconds. Planes are on average waiting $3$ minutes and $15$ seconds for take$-$off. On average there are $17$ planes taking off per hour. How many planes are either on the runway or waiting to take off? $($Round your final answer to $1$ decimal place$)$

Question $9$ options:

$1\mathrm{.}1$ planes in line or taking off

$1\mathrm{.}7$ planes in line or taking off

$2\mathrm{.}1$ planes in line or taking off

$2\mathrm{.}7$ planes in line or taking off

Hide hint for Question $9$

WIP $=$ R x T; WIP$=?$