Oil spilled from a ruptured tanker spreads in a circle whose area increases at a constant rate of 6.5 {\rm mi}^2{\rm /hr}. How rapidly is radius of the spill increasing when the area is 10 {\rm mi}^2?

Question

The radius is increasing at

Answer 1

same question, just change some of the numbers.

http://www.jiskha.com/display.cgi?id=1427938469