A truck owner will refuel his vehicle at a rate of 2 gallons of diesel

Hi All,

This question is essentially one big 'rate' question, but there is an intermediate step that you can take, when solving it, to make the work a little easier to complete. Sometimes a Quant question includes an 'ugly' number that can be 'cleaned up' and made easier to deal with (IF you do a little bit of work to purposely clean it up)...

We're told that a truck owner will refuel his vehicle at a rate of 2 gallons of diesel fuel every 5 seconds and that diesel fuel costs $ 1.25 per gallon. We're asked how long will it take for the truck owner to refuel his vehicle with $40 worth of diesel fuel.

The 'ugly' number in this question is $1.25 per gallon....

1 gallon = $1.25

If we multiply both sides of that equation by 4, we can eliminate the decimal point....

4 gallons = $5.00

Now, it isn't nearly so much work to figure out how many gallons we can buy for $40...

$5 = 4 gallons
$40 = (8)($5) = (8)(4 gallons) = 32 gallons

2 gallons every 5 seconds....
32 gallons = 16(2 gallons) = 16(5 seconds) = 80 seconds.

Final Answer:

GMAT assassins aren't born, they're made,
Rich