Calculusss Helppp!! Urgent..please help with this one!!!

Question

Suppose that fluid is leaking from an overhead pipe and spreading in the shape of a circle on the ground. If the radius of the circle is increasing at a rate of 0.5 feet per minute, how fast is the area of the circle increasing when the radius is 7 feet?

___ft²/min

I got 21.98 but its wrong please help!!

Answer 1

r'=.5 ft/min

A=pir^2

A'=2pirr'=pir= 7pi= about 21.9911 ft^2/sec

you used 3.14 for pi

pi=3.141593...to 6 decimals

use a calculator with a more precise pi value and A'= 21.99 rounded to 2 decimals

pi = 3.142 gives A'=21.99 too