Question

Find the cost to asphalt a circular racetrack if asphalt costs $90 per 100 f2. (Use 3.14 for it. Round to the nearest dollar.) r = 80 ft R = 145 ft

Small circle in a large circle
r= 80 ft
R=145 ft
Y
R
(Use 3.1 4 for a.)

Answer 1

$41,330

Explanation:

To find the cost to asphalt a circular path, first, calculate the area of the circular path:

Area of circular path = area of big circle (A1) - Area of small circle (A2)

Area of circle = πr²

Radius of big circle (R) = 145 ft

Area of big circle (A1) = 3.14*145²

= 3.14*21,025

A1 = 66,018.5 ft²

Radius of small circle (r) = 80ft

Area of small circle (A2) = 3.14*80²

= 3.14*6,400

A2 = 20,096 ft²

=>Area of path = 66,018.5 - 20,096 = 45,922.5 ft²

If 100ft = $90

45,922.5 ft = x

Cross multiply and find x (cost to asphalt the circular path)

100*x = 45,922.5*90

100x = 4,133,025

Divide both sides by 100

x = 4,133,025/100

x = $41,330.25

To the nearest dollar, $41,330 is needed to asphalt the circular path