Question

A parabolic listening device is shaped such that the depth of the bowl depends on its radius and can be represented by the curve D(r) = 0.145r2.
What is the radius when the depth is 8 inches? Round to the nearest thousandth of an inch.
4.417 inches
5.252 inches
7.428 inches
20.505 inches

Answer 1

Answer:

Option (C)

The radius to the nearest thousandth of an inch is 7.428 inches

Step-by-step explanation:

Answer 2

Answer:

Option (C)

The radius to the nearest thousandth of an inch is 7.428 inches

Explanation:

Given the equation is D(r) = $0.145r^2$

Where D is the depth and r is the radius

Putting D = 8 inches in the equation

8 = $0.145r^2$

$r^2$ = $\frac{8}{0.145}$

$r^2$ = 55.2

r = 7.428 inches

The radius of depth is 7.428 inches