Math word problem help needed

Mathematics
Tutor: None Selected Time limit: 1 Day

If 3 bulldozers can load 5 trucks full of earth in 30 minutes, then how long should it take 5 bulldozers to load 7 trucks full of earth? Assume that all the bulldozers work equally hard and all truck loads are the same size. Solve the problem, explaining your reasoning. 

Oct 28th, 2015

Thank you for the opportunity to help you with your question!

Let x = the number of trucks full of earth in 30 minutes

Then to determine how many trucks full of earth 5 bulldozers can load

3/5 = 5/x

Solve for x:

3x = 25

x = 25/3 trucks full of earth in 30 minutes or 25/90 per minute

Then to load 7 trucks:

7 divided by 25/90 = 630/25 = 25.2 minutes

Please let me know if you need any clarification. I'm always happy to answer your questions.
Oct 28th, 2015

Is it possibly for you to explain each step? I'm just a little confused. Thanks!

Oct 28th, 2015

The relationship of the number of bulldozers to the number of trucks full of earth are directly proportional, so

3/5 = 5/x   where x is the number of trucks full of earth that 5 bulldozers can load.

Solving for x we get 25/3 trucks full of earth in 30 minute

Dividing by 30 we find the number of trucks fill per minute, which in this case is 25/3 / 30 = 25/90 trucks full per minute

Then,

7 trucks / 25/90 trucks/min = 25.2 minutes

Oct 28th, 2015

Thank you!

Oct 28th, 2015

Any time.

Oct 28th, 2015

Are you studying on the go? Check out our FREE app and post questions on the fly!
Download on the
App Store
...
Oct 28th, 2015
...
Oct 28th, 2015
Dec 10th, 2016
check_circle
Mark as Final Answer
check_circle
Unmark as Final Answer
check_circle
Final Answer

Secure Information

Content will be erased after question is completed.

check_circle
Final Answer