Math word problem

Question

Kaitlin drove 240 miles using 9 gallons of gas.at this rate, how many gallons of gas would she need to drive 216 miles ?

Answer 1

The easiest way to answer this question is to first determine how many miles Kaitlin can drive with one gallon of gas:

 

240 miles/9 gallons of gas = 26.667 miles/gallon

 

Now, if we know that she drives 216 miles, we can determine:

 

216 miles x (1 gallon/26.667 miles)

 

Crossing out the miles in both the numerator and denominator leaves us with just gallons.  216 divided by 26.667 would be 8.099, or rounding up, 8.1 gallons.

 

ANSWER:  8.1 gallons.

Answer 2

This can be solved using proportions and solving for x.

 

miles   240    216

gal        9       x

 

To find x, cross multiply 9 and 216 

9*216=1944

 

Next, divide the remaining 240 into 1944

1944/240=8.1

 

In other words, at that rate, it would take 8.1 gallons of gas to drive 216 miles.

 

Double check by plugging 8.1 where x is.

 

240    216

  9      8.1

 

Cross multiply 9*216 and 240*8.1. Both equal 1944 so the rate remained consistent, indicating that the answer is correct.