SOLUTION: It has been estimated that 1000 curies of a radioactive substance introduced at a point on the surface of the open sea would spread over an area of 90,000 km2 in 90 days. Assuming

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Question 645107: It has been estimated that 1000 curies of a radioactive substance introduced at a point on the surface of the open sea would spread over an area of 90,000 km2 in 90 days. Assuming that the area covered by the radioactive substance is a linear function of time t and is always circular in shape, express the radius r (in km) of the contamination as a function of t (in days).
I've solved for r with the area of a circle equation since I can't have r in the formula (because it's a function of time), but I literally have no clue where to go next.

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
It has been estimated that 1000 curies of a radioactive substance introduced
at a point on the surface of the open sea would spread over an area of
90,000 km2 in 90 days.
Assuming that the area covered by the radioactive substance is a linear
function of time t and is always circular in shape, express the radius r
(in km) of the contamination as a function of t (in days).
:
Find the radius of a circular area of 90000 sq/km (as you apparently did)
pi%2Ar%5E2 = 90000
r%5E2 = 90000%2Fpi
r = sqrt%2828648%29
r = 169 km is the radius of the substance in 90 days
:
r(t) = 169%2F90t would be the equation