alex.gellatly wrote:Each of the 30 boxes in a certain shipment with either 10 pounds or 20 pounds, and the average (mean) weight of the boxes in the shipment is 18 pounds. If the average weight of the boxes in the shipment is to be reduced to 14 pounds by removing some of the 20 pound poxes, how many 20 pound boxes must be removed?
4
6
10
20
24
We can plug in the answers, which represent the number of 20-pound boxes that should be removed.
Total current weight = 30*18=540.
Answer choice C: 10 of the 20-pound boxes removed.
New total weight = 540 - 10*20 = 340.
New number of boxes = 30-10 = 20.
New average = 340/20 = 17.
The resulting average needs to be smaller, so more 20-pound boxes need to be removed.
Eliminate A, B, and C.
Answer choice D: 20 of the 20-pound boxes removed.
New total weight = 540 - 20*20 = 140.
New number of boxes = 30-20 = 10.
New average = 140/10 = 14. Success!
The correct answer is
D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at
[email protected].
Student Review #1
Student Review #2
Student Review #3
Featured Course
