guerrero wrote:In the "Mashburn" pharmaceutical company there are two machines - a machine that produces blue pills and a machine that produces red pills. The machines are operated 10 hours a day, and the daily quota of the "blue" machine is 20% greater than that of the red machine.
If the "blue" machine was switched on at 8:00am and the "red" machine at 10:45am, at what time will half of the combined daily quota be manufactured?
a) 1:15pm
b) 2:15pm
c) 2:30pm
d) 3:40pm
e) 7:15pm
OA B
I've changed the times to reflect how they would appear on the GMAT.
Let R = the red machine and B = the blue machine.
Each machine produces its daily quota in 10 hours.
Let R's rate = 10 units per hour.
Since B's quota is 20% greater, let B's rate = 12 units per hour.
Total units produced by R and B in 10 hours = (combined rate)(time) = (10+12)(10) = 220 units.
B starts to work at 8am; R starts to work at 10:45am.
The question stem asks at what time half the daily quota -- in other words, 110 units -- will be produced.
We can plug in the answers for the time.
Answer choice C: 2:30pm
Work produced by B in 13/2 hours from 8am to 2:30pm = r*t = (12)(13/2) = 78 units.
Work produced by R in 15/4 hours from 10:45am to 2:30pm = r*t = (10)(15/4) = 37.5 units.
Total work produced = 78+37.5 = 115.5 units.
Since just a bit too much work is being produced, the two machines must work for just a bit less time.
The correct answer is
B.
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