Example on fire$-$fighting

Highest fire risk area is determined by a shopping complex; floor area of ${10}^5{m}^2,$ height equivalent to $2$ stories, estimate fire flow for fire of $2$ hours duration. Hydrant discharge $=1\frac{m^3}{m}in,$ what is the minimum number of hydrants that will be required?.

Estimate for fire flow $Q=0\mathrm{.}004\sqrt[\phantom{2}]{A}$