The temperature at 12 noon was 10C above zero. If it decreases at the rate of 2C per hour until midnight, at what time would the temperature be 8C below zero? What would be the temperature at mid-night?
Can you make it simple please
From the problem we get that:
The temperature at 12 noon is 10o C.
The rate of fall of temp. is 2oC per hour.
The total fall of temp. = 10oC to 0oC from 0oC to -8oC = 18oC
Since the temp. to fall 2o it takes 1 hour
The temp. to fall 18o the time taken will be 1/2 x 18 = 9 hours.
Since the present time is 12 noon and if it takes 9 hours to reach the temp. of -8oC.
Then the time at which the temp. will be -8oC = 9 pm in the night.
Since the temp. at 9 pm is -8oC, the temp at 12 midnight will be (12 - 9 = 3 Hours).
Since falls @ 2o per hour, in 3 hour it will fall = 3 x 2 = 6o.
Then the temp. at midnight will be -8oC + (-6oC) = -14oC.
Ans: 9 pm in the night -14oC.
temperature at 12 noon = 10c
temperature at 1pm = 8c
temperature at 2pm = 6c
temperature at 3 pm = 4c
temperature at 4pm =2c
temperature at 5pm =0c
temperature at 6 pm =-2c
temperature at 7 pm =-4c
temperature at 8 pm =-6c
temperature at 9 pm =-8c
temperature at midnight = -8+-2+-2+-2=-14c