Question

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?

Answer 1

Rate of decrease:

1 hour = 2ºC

Calculate the change in temperature:

Degree = 10 + 8 = 18ºC

Calculate the number of hours needed for the temperature to reach 18ºC:

2ºC = 1 hour

1 ºC = 1 ÷ 2 = 1/2 hour

18ºC = 1/2 x 18 = 8 hours

Calculate the time it will reach 18ºC:

12 noon + 8 hours = 8pm

Answer: It will reach -8ºC at 8 pm

Calculate the number of hours from noon to midnight:

12 noon to midnight = 12 hours

Calculate the temperature dropped in 12 hours:

1 hour = 2ºC

12 hours = 2 x 12 = 24ºC

Calculate the temperature at 12 mid night:

12 noon = 10ºC

12 mid night = 10 - 24 = - 14ºC

Answer: The temperature at midnight will be -14ºC