Answer:
$135.70
Step-by-step explanation:
First step is to calculate the daily consumption for this family of four. Â We'll assume they're all in age to use and flush the toilet themselves (no babies).
So, one person flushes 9.1 gallons a day, a family of 4 would then flush 4 times that:
daily family flushes = 9.1 gal/person * 4 persons/family = 36.4 gal/family
That's for one day... now for a year...
yearly = 36.4 gal/day * 365 days/yr = 13 286 gal/year
Let's convert those gallons into cubic feet:
13 286 gal / 7.48 gal/ft³ = 1,776.2 ft³
Then we multiply the gallons by the price for 100 cubic feet and divide by 100:
1,776.2  ft³ * $7.64 /100 ft³ = $135.70