SOLUTION: Three wheels make 60, 36 and 24 revolutions per minute. Each has a red spot on its rim, which is at the lowest position at time zero. The red spot will all be at this position agai

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Three wheels make 60, 36 and 24 revolutions per minute. Each has a red spot on its rim, which is at the lowest position at time zero. The red spot will all be at this position agai      Log On


   

Question 596279: Three wheels make 60, 36 and 24 revolutions per minute. Each has a red spot on its rim, which is at the lowest position at time zero. The red spot will all be at this position again after:
A. 2 seconds
B. 5 seconds
C. 4 seconds
D. None of these
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
The first wheel spins at 60 rpm which means that it completes 60/60 = 1 revolution every second.

The second wheel spins at 36 rpm. So it completes 36/60 = 0.6 of a revolution every second

The third wheel spins at 24 rpm. So it completes 24/60 = 0.4 of a revolution every second.


So we have the values: 1, 0.6, 0.4

If we wait 10 seconds, then we multiply each value by 10 to get: 10, 6, 4

Now we can divide by the GCF 2 to get 5, 3, 2

This means that it will take 5 seconds for the spots to line up again (since the first number corresponds to the amount of time that has gone by in seconds)