Question

Rosa is filling up the back of her dump truck with cedar mulch for a delivery to a landscaped shopping center. The mulch is being pumped into the truck. After 30 minutes, the truck is 75% full and weighs 33 tons. Fifteen minutes later, Rosa's truck is fully loaded and weighs 42 tons. If Rosa's truck weighs 15 tons when it is empty, what was the rate in tons per minute that the mulch pump took to load the truck?
A. 0.6 tons per minute
B. 0.93 tons per minute
C. 1.07 tons per minute
D. 1.67 tons per minute

Answer 1

In 30 minutes, the truck weighs 33 tons, which means the mulch is 18 tons (33 tons -15 tons from the truck).
In 45 minutes (15 minutes later), the truck weighs 42 tons, which means the mulch is 27 tons.

So from 30 to 45 minutes, 15 minutes elapsed. And in those 15 minutes, 9 tons of mulch was loaded into the truck (27 tons of mulch - 18 tons of mulch).
This can be expressed as $\frac{9 tons}{15 minutes}=0.6tons/minute$