Question 1205690: On a merry-go-round that spins counter-clockwise, 9 horses are evenly spaced on the outside perimeter, numbered clockwise. Abe stands next to horse number 1 and starts counting time as the merry-go-round begins to turn. He notices that It takes six seconds for horse number 4 to reach him. How long will it take the merry-go-round to go all the way around once?
Found 2 solutions by Theo, ikleyn:
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! if it goes all the way around once, then it starts at horse number 1 and ends at horse number 1.
it takes 6 seconds for horse number 4 to reach him.
that's 3 intervals.
they are:
1 to 2
2 to 3
3 to 4
6 seconds divided by 3 equals 2 seconds per interval.
there are 9 intervals for horse him to see horse number 1 pass by again.
9 * 2 = 18 seconds total.
starts at 1, then 2, 3, 4, 5, 6, 7, 8, 9, then 1 again.
count the intervals.
1 to 2
2 to 3
3 to 4
4 to 5
5 to 6
6 to 7
7 to 8
8 to 9
9 to 1
there are 9 intervals to get back to 1 again.
2 seconds each gets you 18 seconds.
Answer by ikleyn(52852)  (Show Source):
You can put this solution on YOUR website! .
On a merry-go-round that spins counter-clockwise, 9 horses are evenly spaced on the outside perimeter,
numbered clockwise. Abe stands next to horse number 1 and starts counting time as the merry-go-round begins
to turn. He notices that It takes six seconds for horse number 4 to reach him. How long will it take
the merry-go-round to go all the way around once?
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In all, there are 9 equal gaps between the neighbor horses along the circumference,
and there are 3 equal gaps from horse 1 to horse 4.
So, the way from horse 1 to horse 4 is one third of the entire circumference.
Therefore, the time for one full revolution is three times 6 seconds, or 3*6 = 18 seconds. ANSWER
Solved.
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