alex.gellatly wrote:Circular gears P and Q start rotating at the same time at constant speeds. Gear P makes 10 revolutions per minute, and gear Q makes 40 revolutions per minute. How many seconds after the gears start roating will gear Q have made exactly 6 more revolutions than gear P?
6
8
10
12
15
Every 60 seconds, Q makes 30 more revolutions than P.
To determine how long it will take Q to make 6 more revolutions, set up the following proportion:
(30 revolutions)/(60 seconds) = (6 revolutions)/(x seconds)
1/2 = 6/x
x = 12.
The correct answer is
D.
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