Question

At a speed of 22 revolutions per minute, how long will it take a wheel of radius 10,

Answer 1

Well, if the radius is 10, then the circumference is $\frac{2*10*22}7=\frac{440}7$
What's the unit? Either way, 22 rev. per minute means each minute you go by $22*\frac{440}7=\frac{9680}7$ units per second. Now you got the linear speed, just find out the time by dividing the distance by the speed!
So, what's the unit for the radius?