5. The temperature at 12 noon was 10°C above zero. If it decreases at the rate of 2°C per hour until midnight, at what time would the temperature be 8°C below zero? What would be the temperature at mid-night?
Given,
Temperature at 12 noon =
Final temperature =
Decrease in temperature =
Time taken for the temperature to decrease by =
Time taken for the temperature to decrease by =
Now,
Time until midnight =
Decrease in temperature in =
Therefore, temperature at midnight =
Therefore, the temperature at mid-night will be below zero.