Oil with specific gravity $0\mathrm{.}8$ pumped steadily through a pipe with a diameter of $20$ cm at

a rate of $100$ gallons per minute.

a$)$ Calculate the mass flow rate $($kg$/$sec$)(10)$

b$)$ If this oil is pumped at this rate to a huge reserve tank of $5$ m diameter and $20-$meter

height, how long it takes $($minutes$,$ seconds$)$ to fill it