SOLUTION: A hard boiled egg has a temperature of 98 degrees celsius. If it is put into a sink that maintains a temperature of 18 degrees celsius, its temperature x minutes later is given by

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: A hard boiled egg has a temperature of 98 degrees celsius. If it is put into a sink that maintains a temperature of 18 degrees celsius, its temperature x minutes later is given by       Log On


   

Question 1032719: A hard boiled egg has a temperature of 98 degrees celsius. If it is put into a sink that maintains a temperature of 18 degrees celsius, its temperature x minutes later is given by
T(x) = 18+80e ^-0.28x. Hilda needs her egg to be exactly 30 degrees celsius for decorating. How long should she leave it in the water?

I am confused on how to set this equation up properly.
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Let +30+=+T%28x%29+=+18%2B80e%5E%28-0.28x%29
==> 12+=+80e%5E%28-0.28x%29
==> 0.15+=+e%5E%28-0.28x%29
==> x+=+-ln0.15%2F0.28+=+6.78minutes