Problem #$1(4\mathrm{.}4$W$)[10$ pts$]$

$($a$)$ A police officer has measured the speed of five vehicles using a radar detector. The speeds were: $35,42,38,51,24mph$ in a $30-mph$ school zone. Calculate the time$-$mean speed and space$-$mean speed.

$($b$)$ If the school zone has a length of $984$ ft $,$ what is the time $($in seconds$)$ it takes for a vehicle to pass the school zone, assuming he$/$she drives at the average speed you have just calculated?