Answer:
The temperature a t = 0 is 190 °F
The temperature a t = 1 is 100 °F
The temperature a t = 2 is 77.5 °F
It takes 1.5 hours to take the coffee to cool down to 85°F
It takes 2.293 hours to take the coffee to cool down to 75°F
Step-by-step explanation:
We know that the temperature in °F, of a cup of coffee t hours after it is set out to cool is given by the following equation:

a) To find the temperature a t = 0 you need to replace the time in the equation:

b) To find the temperature after 1 hour you need to:

c) To find the temperature after 2 hours you need to:

d) To find the time to take the coffee to cool down
, you need to:






e) To find the time to take the coffee to cool down
, you need to:

