A CD makes 581/2 revolutions in 2/4 min.

Complete the unit rate.

In 2/4 minutes the number of revolutions a CD makes = 58 ½ = 117/2

Then

In 1 minute the number of revolutions the CD will make = [ (117/2) / (2/4) ] * 1 = (117 * 4) / (2 * 2) = 117

So it can seen that the CD revolves at the rate of 117 revolutions per minute. I hope this is the answer you were looking for. The procedure for solving this problem is easy for you to understand i hope.

A CD makes 58 1/2 revolutions in 1/2 minutes.

A CD makes 58.5 revolutions in 0.5 minutes.

Multiply both numbers by 2.

A CD makes 117 revolution in 1 minute.