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by d77 » Thu Dec 14, 2006 11:09 am
Circular gears P and Q start roating 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 then gear p?

6
8
10
12
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12
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by thankont » Fri Dec 15, 2006 2:03 pm
One approach could be this :
first case 1/6 rev. per sec
second case 2/3 rev. per sec
if we substitute 12 sec we get 2 rev for first case and 8 rev for second
so difference is 6
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by 800guy » Sat Dec 16, 2006 9:04 pm
thanks, thankont!
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by aim-wsc » Mon Dec 18, 2006 10:27 am
May be a lil exp to answer:

Gear P has 10 revolution per min
& G Q has 40

that means ever one revolution of P, Q revolves around four times.

after 2 revolution of P, Q would have revolved around itself 8 times.
in other words would have made 6 more rotations.

P takes 1/10 mins for one revolution. therefore 12 secs for 2 revolution.
Answer 12
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by Scott@TargetTestPrep » Wed Jun 20, 2018 4:29 pm
d77 wrote:Circular gears P and Q start roating 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 then gear p?

6
8
10
12
15
As we can see, Gear Q makes 30 more revolutions per minute than Gear P does. So, we can set up the following proportion to solve for the number of seconds for Gear Q to make 6 more revolutions than Gear P does:

30 revolutions/1 minute = 6 revolutions/x seconds

We need for both denominators to have the same units. . Since 1 minute = 60 seconds, we can say:

30/60 = 6/x

Cross multiplying, we have:

30x = 360

x = 12

Answer: D

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