Question

The temperature at 12 noon was 10°C above zero. If it decreases at the rate of 2°C per hour until midnight, at what time would the temperature be 8°C below zero? What would be the temperature at mid-night?NCERT Class 7th Mathematics Chapter 1 Integers

Answer 1

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
= 9 hours

Present time is 12 noon so, the time when the temperature is - 8° C
= 12 noon + 9 hours
So, The time at which the temperature will be - 8° C = 9 PM
At 9 PM, the temperature is - 8° C, the temperature at 12 midnight will be = 
(- 8° C) + (- 2° C × 3 hours)
= (- 8° C) + (- 6° C)
= - 14° C

So, at 12 midnight the temperature will be - 14° C.

Answer.

Answer 2

Answer:

-14 degree celcius

Step-by-step explanation:

temperature at 12 noon = 10 degree celcius

at 1=10 - 2 =8 degree celcius

at 2=8-2=6 degree celcius

at 3=6-2=4 degree celcius

at 4=4-2= 2 degree celcius

at 5=2-2=0 degree celcius

at 6=0-2=-2 degree celcius

at 7=-2-2=-4 degree celcius

at 8=-4-2=-6 degree celcius

at9=-6-2=-8 degree celcius

at 10=-8-2=-10 degree celcius

at 11=-10-2=-12 degree celcius

at 12=-12-2=-14 degree celcius

So, the time when temperature would be 8 degree celcius below zero= 9PM,the temperature at midnight (12AM) would be -14 degree celcius.

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