[tex]\begin{gathered} \text{first we have to change the units to gallons, } \\ \text{given that 1 ft}^3=7.48gallons\text{ we have that} \\ 15ft^3=7.48\cdot15gallons=112.2\text{ gallons} \\ so\text{ the time that it would be take to fill that is equal to } \\ \frac{1000000}{112.2}=8912.7\text{ sec = 148.6min or 2.47 hours} \end{gathered}[/tex]
