Question

The temperature at 12 noon was 10º C above zero. If it decreases at the rate of 2
hour until midnight, at what time would the temperature be 8°C below zero? What
be the temperature at midnight?
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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.