A factory has two machines, Machine A and Machine B

Question

A factory has two machines, Machine A and Machine B, producing widgets. Machine A can produce 100 widgets in 5 hours, while Machine B can produce 100 widgets in 8 hours. If both machines work together, how long will it take them to produce 300 widgets?

A) 3 hours
B) 4 hours
C) 5 hours
D) 6 hours
E) 7 hours

A) 3 hours 
B) 4 hours 
C) 5 hours 
D) 6 hours 
E) 7 hours

stne · Answer

If both machines work together then to produce  100  widgets, they would take  \frac{1}{5}+ \frac{1}{8} = \frac{13}{40}

Thus time taken would be  \frac{40}{13}

For  300  Widgets , time taken  \frac{40}{13}*3 = \frac{120}{13}

Not among the options.

Unless I have missed something, kindly check. Thank you.

Ayeka · Answer

Combined rate of A+B= (100/5)+(100/8)=(130/4) 
For producing 300 widgets, Required time = 300/(130/4)=30*4/13=120/13 hrs =9 hrs approx

Locomotivated · Answer

smithgmat123 , please correct the answer choices.

A factory has two machines, Machine A and Machine B

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