A loaf of bread is removed from an oven at 350 degrees F and cooled in a room whose temperature is 70 degrees F. If the bread cools to 210 degrees F in 20 minutes, how much longer will it take the bread to cool to 155 degrees F. Round to the nearest minute.

Answer 1

As you know, Newton's law says that your Temperature function is

T(t) = 70 + 280e^-kt

So, just solve for k in

70 + 280e^-20k = 210

then solve for t in using T(t) = 155.