The most important thing in this problem is understanding and then dividing the given units properly. The first thing that is given is that the CD makes 58 1/2 revolutions in 3/4 minutes. We have to first simplify the number of revolutions made by the CD. This will make the problem in hand very easy.
Number of revolutions made by the CD = 58 1/2
= 117/2
Then
The unit rate = (117/2)/(3/4)
= (117 4)/(2 3)
= (117 2)/3
= 39 2
78
So the unit rate is 78 revolutions per minute.
