Question

the temperature at12noon was 10°c above zero if it decrases at the rate of 2°c per hour until mid night , at what time would the temperature be 8°c below zero ? what would be the temperature at midnight

Answer 1

First of all you need to understand that it is written in question that the temperature was 10℃ above zero which means 10℃ and it is written that the temperature was 8℃ below zero which means -10℃.

Current temperature = 10℃
Time when it was 10℃ = 12 pm
Rate by which temperature decreases = 2℃/hr
Temperature to be reduced till = -8℃

Time = 12 pm
Temperature = 10 ℃

Time = 1 pm
Temperature = 8℃

Time = 2 pm
Temperature = 6℃

Time = 3 pm
Temperature = 4℃

Time = 4 pm
Temperature = 2℃

Time = 5 pm
Temperature = 0℃

Time = 6 pm
Temperature = -2℃

Time = 7 pm
Temperature = -4℃

Time = 8 pm
Temperature = -6℃

Time = 9 pm
Temperature = -8℃

So, the temperature was -8℃ (8℃ below zero) at 9 pm.

Now, to find the temperature at midnight:

Time = 9 pm
Temperature = -8℃

Time = 10 pm
Temperature = -10℃

Time = 11 pm
Temperature = -12℃

Time = 12 pm
Temperature = -14℃

So, the temperature at midnight will be -14℃.

Answer 2

it is given in the question
temperature at 12 noon = 10°c
Also,
change in temperature per hour= -2°c
Therefore,
temperature at 1:00pm = 10°c +(-2°c)= 8°c
temperature at 2:00pm = 8°c + (-2°c) = 6°c
temperature at 3:00 pm =6°c +(-2°c)= 4°c
temperature at 4:00pm = 4°c +(-2°c) =2°c
temperature at 5:00pm =2°c +(-2°c) =0°c

temperature at 6:00 pm= 0°c+(-2°c)
temperature at 7:00pm= -2°c + (-2°c)=-4°c
temperature at 8:00 pm = -4°c + (-2°c) =-6°c
temperature at 9:00 pm = -6° c +(-2°c) = -8°c

Hence,
the temperature will be 8° c below zero at 9:00 pm
Now,
change in temperature in 12 hour = -2°c×12 =-24°c.
Also,
at midnight the temperature will be= 10+(-24) =-14°c
Hence,

the temperature at midnight will be -14°c below zero..

I Hope helpful
thanks