Answer
$3.69\times10^6 \ gallons$
Work Step by Step
We know that there are 600 GW, and they are used in a day, which has 24 hours in it. Thus, we find:
$=600\times24=14,400 \ Gwh$
Now, we can convert, using conversions from Appendix C:
$14,400 \ Gwh\times \frac{1,000,000 \ kwh}{Gwh}\times \frac{gal}{39 \ kwh}=3.69\times10^6 \ gallons$
