How Does Newton's Law of Cooling Predict Time for Temperature Changes?

[dymand68]

Homework Statement

A container of hot water at 80°C cools to 79°C in 15 seconds when it is placed in a room that is at 20°C. Use Newton's law of cooling to estimate the time it will take for the container to cool from 70°C to 69°C.
And still later, from 30°C to 29°C.

Homework Equations

rate~change in temp.

The Attempt at a Solution

15*1.125=18.75 (incorrect)

 

[ehild]

Look after Newton's law of cooling.

ehild