Question

You place a cup of 205oF coffee on a table in a room that is 72oF, and 10 minutes later, it is 195oF. Approximately how long will it be before the coffee is 180oF? Use Newton's law of cooling:




1 hour

25 minutes

15 minutes

45 minutes

Answer 1

As I recall, our model is

T(t) = 205 + (72-205)e^-kt

So, solve for k in T(10) = 195
Then use that k to solve for t in T(t) = 180

What do you get?

Answer 2

oh okay i got 25 minutes, is that right?