College Algebra & Trigonometry, 2018a

3.1. EXPONENTIAL AND LOGISTIC APPLICATIONS 155
5) A Temperature Model
A cup of coffee is heated to 180 ◦ F and placed in a room that maintains a temperature
of 65 ◦ F . The temperature of the coffee after t minutes have passed is given
by:
F (t) = 65 + 115e −0.042t
a) Find the temperature of the coffee 10 minutes after it is placed in the room.
Round your answer to the nearest degree.
b) When will the temperature of the coffee be 100 ◦ F ?
Round your answer to the nearest tenth of a minute.
6) A Temperature Model
Soup at a temperature of 170 ◦ F is poured into a bowl in a room that maintains
a constant temperature. The temperature of the soup decreases according to the
model given by:
F (t) =75+95e −0.12t
where t is the number of minutes that have passed since the soup was poured.
a) What is the temperature of the soup after 2 minutes?
Round your answer to the nearest 10th of a degree.
b) A certain customer prefers that the soup be cooled to 110 ◦ F .
How long will this take?
Round your answer to the nearest 10th of a minute.