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?
Initial temperature i.e., at 12 noon = 10°C
Change in temperature per hour = −2°C
Temperature at 1:00 PM = 10ºC + (−2ºC) = 8ºC
Temperature at 2:00 PM = 8ºC + (−2ºC) = 6ºC
Temperature at 3:00 PM = 6ºC + (−2ºC) = 4ºC
Temperature at 4:00 PM = 4ºC + (−2ºC) = 2ºC
Temperature at 5:00 PM = 2ºC + (−2ºC) = 0ºC
Temperature at 6:00 PM = 0ºC + (−2ºC) = −2ºC
Temperature at 7:00 PM = −2ºC + (−2ºC) = −4ºC
Temperature at 8:00 PM = −4ºC + (−2ºC) = −6ºC
Temperature at 9:00 PM = −6ºC + (−2ºC) = −8ºC
Therefore, the temperature will be 8°C below zero at 9:00 PM.
It will take 12 hours to be midnight (i.e., 12:00 AM) after 12:00 noon.
Change in temperature in 12 hours = −2°C × 12 = −24ºC
At midnight, the temperature will be = 10 + (−24)
Therefore, the temperature at midnight will be 14ºC below 0.
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