Question

16. When Laura finishes cooking, her oven

temperature is 400°F. If her oven cools at a rate of
3.25°F per minute, how many minutes will it take
for her oven to reach 75°F? Enter your response in
the gridded area.
DW

Answer 1

Her oven will cool to 75°F in 100 minutes, or 1 hour 40 minutes.

Explanation:

Let T(t) represent the oven temperature, and t the time in minutes.

Then:

T(t) = 400°F - (3.25°F/min)t

Find the time, t, at which T(t) will = 75°F:

400°F - (3.25°F/min)t = 75°F

Subtracting 75°F from both sides, we get:

(3.25°F/min)t = 325°F.

Dividing both sides by (3.25°F/min) yields:

t = 100 minutes.

Her oven will cool to 75°F in 100 minutes, or 1 hour 40 minutes.