A thermometer reading 10C is brought into a room with a constant temperature of 30C. If the thermometer reads 15C after 2 ​minutes, what is it at 4 ​minutes? For 9 ​minutes?

Answer 1

It went up 5 degrees in 2 minutes.

It will rise 10 degrees in 4 minutes, so 20C.

5/2 = x/9

2x = 45

x = 22.5

It will be 32.5 degrees in 9 minutes.

Optionally you can argue that the temperature increases 5/2 = 2.5 degrees every minute.

So the linear function is y = 2.5x + 10

which produces temperatures of 15, 20, and 32.5 degrees for x=2,4, and 9 respectively