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 8oC below zero? What would be the temperature at midnight?

Answer 1

Let noon be time t = 0 hr.,
then the temperature T in degrees Celsius at t hr. would be:
T = 10 - 2t

Now,

To find when the temperature is 8°C below zero,

T = -8

10 - 2t = -8

2t = 18

t = 9

Thus, the temperature is 8°C below zero at 9:00 pm.

To find the temperature at midnight,
use t = 12:00
T = 10 - 2(12) = 10 - 24 = -14
Thus, the temperature at midnight is 14∘C below zero.


Hope this helps you...,

Answer 2

Solution : Temperature at 12 Noon = 10°C above 0°C = 10°C

              It decreases at 2° per hour.

Final temperature = 8°C below 0 = -8°C


Change in temperature = 10 - ( -8 ) = 18°C.

Rate of decrease = 2° per hour.


Time = 18 / 2 = 9 hours.


So, Time at which temperature would be 8°C below zero = 12:00 + 9:00 = 21:00

                  So, the time at which temperature goes 8°C below 0 is 9:00 PM.


Also, The temperature at 12 :00 PM = 10° C, As temperature decreases at 2°C,


Temperature at mid night = 10° C - 2 ( 12 ) = 10 - 24 = -14° C.


Hope helped!