In order to calculate the rate, we calculate the variation of temperature and time
then, calculate the rate by dividing the variation of temperature by the variation of time
the rate is equal to -2°C per hour, then from 8:00 pm to 11:00 pm, there is a difference of 3 hours.
Multiply the time by the rate:
The temperature drops another 6°C, then,
Answer:
The temperature will be about -23°C