Source: Official Guide for the GMAT 13th Ed. Problem Solving; #23 Official Guide for the GMAT 2015 14th Ed. Problem Solving; #23


Running at the same constant rate, 6

Running at the same constant rate, 6 identical machines can produce a total of 270 bottles per minute. At this rate, how many bottles could 10 such machines produce in 4 minutes?

4 Explanations


Christoph Mader

I came to (B) with an estimation, I'm not quite sure though if it is a 100% correct but the easiest way would be:

6 Machines -> 270 bottles / min
12 Machines -> 540 bottles / min

in 4 minutes -> 540*4 = 2160

So (C), (D), (E) are out of question already
(A) is out of question as well because 270*4 > 648, so 4 Machines would already produce more then 648.

Only suitable answer -> (B)

Aug 25, 2019 • Comment

David Recine, Magoosh Tutor

That is a great way to estimate/ballpark!

Aug 26, 2019 • Reply


Joseph R Ross

Used the mental math concept of "estimation" explained in the intro to math videos, since the answers were spread apart.
1. Rounded up 270 to 300, which is easily divided by 6. So roughly one machine can produce 50 bottles per minute.
2. 10 machines * 50 bottles = 500 bottles per min.
3. 500 bottles per min * 4 mins. = roughly 2000 bottles
4. Taking into account the rounding up in beginning, the closest answer is 1800 bottles.

May 9, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Great job using those concepts to efficiently solve the question :) Thanks for sharing your method!

May 12, 2016 • Reply



In 1 min: 270/6=x/10 (x is no of bottles by 10machines)
x=450 bottles per min x 4mins= 1800btls

May 14, 2014 • Comment

, Magoosh Tutor

That's another way to solve too. :)

May 15, 2014 • Reply


Gravatar Mike McGarry, Magoosh Tutor

Dec 27, 2013 • Comment

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