Question

the temperature at 12 noon at certain place was 12 degrees above zero , if it decreases at the rate of 2 degree per hour until midnight at what time would it be 10 degree below zero

Answer 1

At 11 o'clock.
You have to Go through 22 degrees in all.
Rate of Dropping of temperature =2 degrees/ hour
Hence to Come to to 22 degrees You need 22/2= 11 hours.
Starting from 12 noon.
12+11=23hrs. i.e. @ 11 pm

Answer 2

Hello Friend
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Here's your answer

The temperature decreases at a rate of 2degrees per hour

It was actually 12 degree above zero

We need to find at what time does the the temperature drops down to 10 degree below zero that is -10

Temperature change = 12-(-10)

=12+10

=22

For one hour it drops by 2degree

So it takes 22/2=11hours to attain -10 degree

It means, at 11'o clock e temperature falls down to -10 degree
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Hope it helps!