Acar tire has a radius of 1.5 feet. if the tire is rotating at 800 rpm, what is the speed of the car in miles per hour (1 mile = 5,280 feet)? round the answer to the nearest tenth.

The first the is to find the distance covered when the wheel makes one rotation.

circumference = 2π×1.5=9.424778 feet

In one minute the car would cover (9.424778×800)= 7,539.822369 feet

Speed = distance/time
time = 1 minute = (1/60) hours
distance = (7,539.822369/5280)=1.427996661 miles

∴ speed =  1.427996661÷(1/60)
              = 85.7 miles per hour

The first answer is correct