If this is a piece of paper, you are Live, and you can submit your answers on the back of this piece of paper. Please put your name at the top of the back and number your calculations from 1 through 4.

If this is a computer screen, you are Electric, and you can submit your answers to your teacher as your teacher directs. Please put your name and the number of the problem (1, 2, 3 or 4) at the top of each problem you submit answers for.

Math Problem 4 - After reading the note above, maybe you wonder about using solar panels to make a car go, like the kids at MIT do in their annual contest. But after some checking, you find that solar panels would cost more than the $500 your dad is willing to spend, plus of course he’d need an electric motor. Still, you like the idea of not having to ask for gas money once you start driving. Luckily, somebody told you about how diesel motors can run on clean used kitchen grease, and since your dad drives a diesel pickup, you have found out that for about $900 you could convert your dad’s pickup to run on used grease, and that after that he wouldn’t have to use diesel fuel except at the very beginning and very end of each trip. You've also learned that the burger joint you go to all the time has to pay $35/month to have their 50 gallon barrel of grease drained each month, and that they'd just as soon pay you since you're a customer. The chief problem is selling dad. Assuming his annual milage is 10,000 and he gets 15 miles per gallon at a time when diesel costs $3 all year long, figure out how long it would take to make the conversion kit pay for itself. Answer in the form of years, spelling out any fractional portion as months, weeks, hours, etc. Assuming you figured about half a year, show how you arrived at this conclusion.

Likely time to solve: 10 min.

What counts on the report card: Arithmetic 7