Math in the Workplace: Overview

Math in the Workplace - Measurements / Geometry

Problem:

A man wants to put in a 4-foot wide sidewalk around his ice rink. The rink is a circle, 120 feet in diameter. The 4-foot wide sidewalk needs to be 4 inches thick.

How many cubic yards of cement are needed for the sidewalk?

Solution:  

Calculate the area of the rink and the area of the rink plus the sidewalk.

120 2 = 60 ft. (radius of ice rink)
120 + 8 = 128 2 = 64 ft (radius of ice rink and sidewalk)

A = pr²

p(60)²  = 11,309.7 sq. ft. (area of rink)

p(64)²  = 12,868.0 sq. ft. (area of rink and sidewalk)

12,868.0 - 11,309.7 = 1,558.3 sq. ft. in sidewalk

(1558.2 sq.ft)(4 in.)(1 ft.12 in.)(1 cu. yd.27 cu. ft.) = 19.2 cu.yd

Math in the Workplace: Overview