Question 477077
A person is riding on a ferris wheel that turns at a constant speed.
 The lowest point of the wheel is at the ground level.
 Another person is standing at the side of the wheel on a platform 4 m above the ground.
 She notes the times the person on the wheel is on the same level as she is. 
the intervals between 2 successive times they are on the same level is 6 sec and 18 sec.
What is the radius of the wheel?
:
From the description of the ferris wheel, we can say a complete rev = 24 sec:
the point on the wheel from the lowest point to 4 m above ground takes 3 sec.
The time from the lowest point to the highest point takes 12 sec, let this = 2r
:
Assume the relationship to be: {{{(2r)/4}}} = {{{12/3}}}
Cross multiply
3(2r) = 4 * 12
6r = 48
r = 8 m is the radius of the wheel