Question

5. 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?​

Answer 1

Answer:

Change in temperature = 10 - ( -8 ) = 18°C. Rate of decrease = 2° per hour. Time = 18 / 2 = 9 hours. So, the time at which temperature goes 8°C below 0 is 9:00

Answer 2

Step - By - Step Explanation:

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.

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