From the question is given that,
Temperature at the beginning i.e., at 12 noon = 10°C
Rate of change of temperature = - 2°C per hour
Then,
Temperature at 1 PM = 10 + (-2) = 10 – 2 = 8°C
Temperature at 2 PM = 8 + (-2) = 8 – 2 = 6°C
Temperature at 3 PM = 6 + (-2) = 6 – 2 = 4°C
Temperature at 4 PM = 4 + (-2) = 4 – 2 = 2°C
Temperature at 5 PM = 2 + (-2) = 2 – 2 = 0°C
Temperature at 6 PM = 0 + (-2) = 0 – 2 = -2°C
Temperature at 7 PM = -2 + (-2) = -2 -2 = -4°C
Temperature at 8 PM = -4 + (-2) = -4 – 2 = -6°C
Temperature at 9 PM = -6 + (-2) = -6 – 2 = -8°C
∴At 9 PM the temperature will be 8°C below zero
Then,
The temperature at mid-night i.e., at 12 AM
Change in temperature in 12 hours = -2°C × 12 = - 24°C
So, at midnight temperature will be = 10 + (-24)
= - 14°C
So, at midnight temperature will be 14°C below 0.
