The temperature of a place at midnight is 9°C. If the temperature drops at the rate of 3°C per hour, after how many hours will the temperature become −6°C?
Answers
QUESTION:-
The temperature of a place at midnight is 9°C. If the temperature drops at the rate of 3°C per hour, after how many hours will the temperature become −6°C?
SOLUTION:-
At 12 noon, the temperature =10°C above zero
The temperature is decreasing at 2°C per hour
8°C below zero =−8°C
So, total fall in temperature from 10°C to 0°C and from 0°C to −8°C=18°C
Since the temperature falls 2°C in every one hour.
Therefore, to decrease 18°C, time taken = 18/2
Therefore, to decrease 18°C, time taken = 18/2= 9 hours
Present time is 12 noon so, the time when the temperature is −8°C
=12noon+9hours
So, The time at which the temperature will be −8°C=9PM
At 9 PM, the temperature is −8°C, the temperature at 12 midnight will be =
(−8°C)+(−2°C×3hours)
=(−8°C)+(−6°C)
=−14°C
So, at 12 midnight the temperature will be−14°C.
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