<PRE><B>Question 515161</B>
The 20 inch diameter wheels of one car travel at a rate of 24 revolutions per minute, while the 30 inch diameter wheels of another car travel at a rate of 18 revolutions per minute. What is the ratio of the speed of the second car to that of the first?
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For car with 20 inch wheels:
circumference=2&amp;#960;r=2&amp;#960;*10=20&amp;#960; inches
speed of car=24rev/min*20&amp;#960; inches/rev=48&amp;#960; inches/min
..
For car with 20 inch wheels:
circumference=2&amp;#960;r=2&amp;#960;*15=30&amp;#960; inches
speed of car=24rev/min*30&amp;#960; inches/rev=72&amp;#960; inches/min
..
speed of 2nd car/speed of 1st car=72/48=3/2</PRE>