An earthworm can travel 24 feet in an hour. Which of the following is equivalent to this rate? a.) 120 inches per minute b.) 4.8 inches per minute c.) 30 inches per minute d.) 0.2 inches per minute

To convert feet per hour to inches per minute, you need to use the conversion factors 12 inches = 1 foot and 60 minutes = 1 hour. Start by converting feet to inches:

fraction numerator 24 space horizontal strike f e e t end strike over denominator 1 space h o u r end fraction times fraction numerator 12 space i n c h e s over denominator 1 space horizontal strike f o o t end strike end fraction equals fraction numerator 288 space i n c h e s over denominator 1 space h o u r end fraction

Notice how the units of feet in the first fraction cancel out the units of feet in the second fraction. Now change hours to minutes:

fraction numerator 288 space i n c h e s over denominator 1 space horizontal strike h o u r end strike end fraction times fraction numerator 1 space horizontal strike h o u r end strike over denominator 60 space m i n u t e s end fraction equals fraction numerator 4.8 space i n c h e s over denominator m i n u t e end fraction