The rate at which he pumps water is [tex] \frac{1500gal}{min} [/tex].
To find the number of hours it takes to pump 0.9 million gallons, we can set a proportion.
[tex]\frac{1500gal}{min} = \frac{0.9*100000}{x} \\ \\ 1500x = 0.9*1000000 \\ x = 900000/1500 = 600min[/tex].
The question asks for the time in hours, so convert 600 min to hours. One hour is 60 min.
[tex]600min* \frac{hr}{60min} = 10hr[/tex]