# of revolutions? Please help.

[nathanralph]

for some reason I just can't get this one.

 

[stapel]

What have you tried? You've found the radius, and plugged this into the appropriate formula to find the circumference of the tire, which is also the distance covered in one revolution of the tire. You've converted from "miles per hour" to "feet per minute", to find the distance covered in one minute. And... then what?

Eliz.

 

[tkhunny]

This is an excellent example of a problem where much of what you need is not given in the problem statement.

You need to know,
1) Tires are circular
2) Circumference of a circle = 2*pi*radius = pi*diameter
3) 12 inches in 1 foot
4) 5280 ft in 1 mile
5) 60 minutes in 1 your

OK, now what?

 

[nathanralph]

All right I got it now...I was over-complicating it. Thanks for putting me in the right direction.

Circumference (in feet) = 6.021385913
5280 feet in one mile.

5280/6.021385913 = 876.8745396 or 878 rounded.

878 revolutions per minute.

Many thanks!