A personal sampling pump was turned on at $8$:$05AM$ and continued until $12$:$31PM$; it was

turned back on at $1$:$18$PM and off again at $4$:$52$PM$.$ How many hours of sampling time were

logged?

Using the sampling time of Problem $1,$ what flow rate would be necessary in order to collect

$1920$ liters of air?

An air sampling protocol for bromine calls for sampling at least $30,500$ milliliters of air.

Calculate the minimum time necessary for sampling when using a pump with a flow of $0\mathrm{.}8$

liters per minute.