Answer: The temperature dropped 8 degrees.
Explanation:
The initial temperature was T0, and each hour the temperature dropped by 2°, for 4 hours.
So we can write the temperature as a function of time in the next way:
T(t) = T0 - (2°/h)*t
where t is the number of hours since the temperature started to drop.
The temperature drop for four hours, so we have that the final temperature is:
T(4h) = T0 - (2*4)°= T0 - 8°
then we can calculate the difference between the final and initial temperature as:
T(4h) - T(0h) = T0 - 8° - T0 = -8°
This means that in Friday morning the temperature dropped by 8 degrees.