A car's wheels are 28" in diameter. How far (in miles) will the car travel if its wheels revolve 10,000 times without slipping?

Question

anonymous · Answer

for one revolution of a wheel car travels 2*pi*14 ins
10000  revs  =  2*pi*14* 10,000 ins
  = ( 2*pi*14* 10,000) /  (5280*12) miles
  =  13.883 miles

turingtest · Answer

convert miles to inches
(12in/ft)(5280ft/mi)=63360in/mi
C=(pi)d=28pi=distance of one revolution in inches
28pi(10,000)=280000pi inches
convert to miles:
280000/63360=4.419 miles
hey I which one of us messed up jimmyrep?

turingtest · Answer

oh id did (forgot to use pi)
4.419(pi) miles=13.883 miles
my bad

anonymous · Answer

Jimmyrep : where did the 12 come from when multiplying by 5280? and that answer was correct. I have the answers in the back of my book. I just didn't understand how to get it.

turingtest · Answer

to get inches/mile you must do a conversion:
12(inches/foot)x5280(feet/mile)=63360(inches/mile)

anonymous · Answer

yes 5280 ft to mile 12 ins to a ft

turingtest · Answer

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the "feet" cancel