Bunuel
If it would take one machine 10 minutes to fill a large production order and another machine 12 minutes to fill the same order, how many minutes would it take both machines working together, at their respective rates, to fill the order?
A. 4 1/60
B. 5
C. 5 5/11
D. 5 1/2
E. 11
PS21161
With most work questions, a useful approach is to
assign a "nice" value to the total job.
We want a number that works well with the given numbers, 10 and 12
So, let's say the production order consists of making
120 widgets
It would take one machine 10 minutes to fill the production orderRate = output/ time =
120/10 = 12 widgets per minute
It would take the other machine 12 minutes to fill the production orderRate = output/ time =
120/12 = 10 widgets per minute
COMBINED rate of both machines = 12 + 10 =
22 widgets per minute
How many minutes would it take both machines working together, at their respective rates, to fill the order?Time = output/rate =
120/
22 = 60/11 =
5 5/11 minutesAnswer: C
Cheers,
Brent