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Bunuel
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Jason can stack two shelves in 3 hours and Maria can stack three shelv 28 Jul 2017, 08:55
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B
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5% (low)

Question Stats:

85% (01:30) correct 15% (02:04) wrong based on 184 sessions

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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
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B
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Jason can stack two shelves in 3 hours and Maria can stack three shelv 28 Jul 2017, 09:01
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Bunuel
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
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Jason = \(\frac{3}{2}\) Shelves/Hour

Maria = \(\frac{2}{3}\) Shelves/Hour

Together Jason and MAria = 3/2 + 2/3 = 13/6 Shelves/Hour

Time taken for 13 shelves working together = \(\frac{13}{{13/6}}\) = 6 Hours

Hence, Answer is B
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Jason can stack two shelves in 3 hours and Maria can stack three shelv 28 Jul 2017, 11:09
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13/(2/3+3/2).
This yields 6.

Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app
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Jason can stack two shelves in 3 hours and Maria can stack three shelv 30 Jul 2017, 00:32
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Bunuel
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
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J 2 shelves 3 hrs = 4 shelves 6 hrs
M 3 shelves 2 hrs= 9 shelves 6 hrs

J+M = 13 shelves 6 hrs

B
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Jason can stack two shelves in 3 hours and Maria can stack three shelv 30 Jul 2017, 01:47
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If Jason can stack 2 shelves in 3 hours,
he could stack a shelf in 1.5 hours, or in an hour he would have completed \(\frac{2}{3}\)rd(0.67) of the shelf.
Similarly, since Maria can stack 3 shelves in 2 hours, so she would complete \(1\frac{1}{2}\)(1.5) shelves in an hour.

Together, they would complete \(2\frac{1}{6}\)th(2.17) shelf in an hour, and it would take them 6 hours to do 13 shelves(Option B)
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Jason can stack two shelves in 3 hours and Maria can stack three shelv 31 Jul 2017, 14:09
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It takes Jason 3hrs to stack 2 shelves
therefore he stacks 1 shelf in 1.5 hrs
It takes Maria 2 hrs to stack 3 shelves
Therefore she stacks 1 shelf in 0.66 hrs
Total shelves to be stacked = 13
Therefore time taken to stack 13 shelves= 13/(1.5+0.66) ~ 6
Answer-(b)
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Jason can stack two shelves in 3 hours and Maria can stack three shelv 20 Aug 2018, 11:49
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Bunuel
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
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The combined rate of Jason and Maria is 2/3 + 3/2 = 4/6 + 9/6 = 13/6.

So it takes them 13/(13/6) = 13 x 6/13 = 6 hours to stack 13 shelves.

Answer: B
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