Question

The temperature at 12 noon was 10 degree cercus above zero.If it decreases at the rate of 2degree cercus per hour until midnight,at what time would the temperature be 8degree cercus below zero?What would be the temperature at mid-night?

Answer 1

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.