Brian rides his bike for 7.5 miles. The diameter of his bicycle tires is 20 inches. Estimate the

number of complete rotations his bicycle tires make during the ride. Round to the nearest 10

complete revolutions. (Notes: 1 foot = 12 inches, and 5280 feet = 1 mile)

7500 revolutions

Step-by-step explanation:

1 rotation of his bicycle tires is equivalent to 1 circumference in linear distance.

circumference = π*diameter = π*20 = 62.8 in

If 1 foot is equivalent to 12 inches, then 62.8 in are equivalent to:

1 ft / x ft = 12 in / 62.8 in

x = 62.8/12 = 5.2 ft

If 5280 ft are equivalent to 1 mile, then 5.2 ft are equivalent to:

5280 ft / 5.2 ft = 1 mile / x mile

x = 5.2/5280 = 0.001 mile

So, when 1 revolution is made, 0.001 mile had been travelled. To compute the number of revolutions after 7.5 miles are travelled, the following proportion must be satisfied:

1 revolution / x revolutions = 0.001 mile / 7.5 miles

x = 7.5/0.001 = 7500 revolutions