A pool can hold 30,000 gallons of water. If is $\frac{1}{4}^{th}$ full. A pump can deliver $'g'$ gallons of water every $m$ minute. If the pumping company charges $'d'$ dollars per minutes, how much will it cost in dollars to fill the pool ?

Question

$\begin{array}{1 1} (a)\; \frac{5000 \;md}{g} \\ (b)\; \frac{5000\; mg}{d} \\ (c)\; \frac{7500 \; md}{g} \\ (d)\; \frac{7500\; mg}{d} \end{array}$