Working alone Jane can assemble 9 model cars in 7 hours, how long will

Question

Working alone Jane can assemble 9 model cars in 7 hours, how long will it take her to assemble 12 model cars?

A. 9/7
B. 7/12
C. 28/3 
D. 10
E. 14

quantumliner · Answer

Rate of assembling Car = 7/9

Time taken to assemble 12 cars = 12 * 7/9 = 28/3

Answer is C. 28/3

BrentGMATPrepNow · Answer

Given: Jane can assemble 9 model cars in 7 hours  
RATE = output/time 
= (9 cars)/(7 hours) 
=  9/7  cars/hour

How long will it take her to assemble 12 model cars?  
Time = output/rate = 12/( 9/7 )
= (12)(7/9)
= 84/9
= 28/3 hours

Answer: C

BPHASDEU · Answer

Ans C.

W = R * T => T = W / R => T = 12 / (9/7) = 12* 7/9 =  28/3

gvvsnraju@1 · Answer

7 hrs = 9 models
7/9 hrs = 1 model
7/9*12 hrs = 12 model
Ans = 28/3

matthewsmith_89 · Answer

9 model cars = 7
1 model cars = 7/9
12 model cars
=7/9 x 12
= 28/3

Which is answer C

KrishnakumarKA1 · Answer

9 cars is assembled in 7 hrs
1 car is assembled in 7/9 hrs
12 cars is assembled in (7/9) x 12 = 28/3 hours

Option C

EMPOWERgmatRichC · Answer

Hi All,

This is essentially just a 'rate' question, but there's a built-in shortcut based on the numbers involved...

We're told that Jane can assemble 9 model cars in 7 hours. We're asked how long it would take her to assemble 12 cars....

Since 12 is '1/3 greater' than 9, the time to make 12 cars will be '1/3 greater' than 7 hours.

7 + 7(1/3) = 7 + 2 1/3 = 9 1/3 hours

Final Answer:  C

GMAT assassins aren't born, they're made,
Rich

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