Magoosh
Jason can stack two shelves in 3 hours and Maria can stack three shelves in 2 hours. How long will it take them together, working at a constant rate, to stack thirteen shelves?
A. 5 hours
B. 6 hours
C. 6.5 hours
D. 11 hours
E. 12 hours
OA B.
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Jason can stack two shelves in 3 hours and Maria can stack
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Jason can stack two shelves in 3 hours and Maria can stack
Thu Aug 16, 2018 5:16 am
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Rich.C@EMPOWERgmat.com
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Thu Aug 16, 2018 2:39 pm
Hi All,
We're told that Jason can stack 2 shelves in 3 hours and Maria can stack 3 shelves in 2 hours. We're asked how long will it take them together, working at their constant rates, to stack thirteen shelves. This question is a 'rate' question, so you can work through the math in a number of different ways. Here's an approach that puts both rates in terms of 'output per hour':
Jason stacks 2 shelves every 3 hours, so he stacks 2/3 of a shelf per hour.
Maria stacks 3 shelves every 2 hours, so he stacks 3/2 of a shelf per hour.
Combined, they stack 2/3 + 3/2 = 4/6 + 9/6 = 13/6 shelves per hour.
We're asked how long it would take for the two to stock 13 shelves....
(X)(13/6 shelves/hour) = 13 shelves
X = 13(6/13) = 6 hours
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
We're told that Jason can stack 2 shelves in 3 hours and Maria can stack 3 shelves in 2 hours. We're asked how long will it take them together, working at their constant rates, to stack thirteen shelves. This question is a 'rate' question, so you can work through the math in a number of different ways. Here's an approach that puts both rates in terms of 'output per hour':
Jason stacks 2 shelves every 3 hours, so he stacks 2/3 of a shelf per hour.
Maria stacks 3 shelves every 2 hours, so he stacks 3/2 of a shelf per hour.
Combined, they stack 2/3 + 3/2 = 4/6 + 9/6 = 13/6 shelves per hour.
We're asked how long it would take for the two to stock 13 shelves....
(X)(13/6 shelves/hour) = 13 shelves
X = 13(6/13) = 6 hours
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
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GMATGuruNY
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Thu Aug 16, 2018 3:01 pm
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Jeff@TargetTestPrep
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Mon Aug 20, 2018 10:48 am
AAPL wrote:
The combined rate of Jason and Maria is 2/3 + 3/2 = 4/6 + 9/6 = 13/6.
Magoosh
Jason can stack two shelves in 3 hours and Maria can stack three shelves in 2 hours. How long will it take them together, working at a constant rate, to stack thirteen shelves?
A. 5 hours
B. 6 hours
C. 6.5 hours
D. 11 hours
E. 12 hours
Jason can stack two shelves in 3 hours and Maria can stack three shelves in 2 hours. How long will it take them together, working at a constant rate, to stack thirteen shelves?
A. 5 hours
B. 6 hours
C. 6.5 hours
D. 11 hours
E. 12 hours
So it takes them 13/(13/6) = 13 x 6/13 = 6 hours to stack 13 shelves.
Answer: B
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