How much does it cost to run 300 school buses for 22 days?

[samona]

Homework Statement

A large school district has 300 school buses. If each school bus is used 3 hours each day, the average speed of the school buses is 15 mi/h, and the fuel economy of the buses is 10 mi/gal. How much does it cost to run these buses in 22 school days if gasoline costs $1.20 a gallon?

2. The attempt at a solution

I've been trying to figure out this problem for hours now. This is what I've done, but the book says I'm incorrect.

My attempt:

Find out what it costs to run one bus a day.

3 hrs/day x 15 mi/hr x 1gal/10mi x $1.20/gal = $5.40 per day for 1 bus.

There are 300 buses, so $5.40 x 300 = $1620 for 300 buses.

The problem asks the cost for running the buses for 22 school days, $1620 * 22 = $35,640.

My final answer is that it would cost $35,640 to run 300 buses for 22 days. Please help me figure out where I am going wrong.

 

[phyzguy]

Your analysis looks good to me. What does the book say is the right answer?

 

[samona]

Thanks for the quick response. The answer seems to be $216.

 

[phyzguy]

I think that $216 can't possibly be the right answer to the problem you posed. Are you sure you copied it correctly?

 

[samona]

I'll double check when I get home tonight. I appreciate your help!

 

[samona]

Sorry for the late response. Book has the answer as $1200.

 

[Delphi51]

Your $35640 matches my calc exactly!