Question

6. 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 midnight?

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Answer 1

Answer:

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

=12noon+9hours

So, The time at which the temperature will be −8°C=9PM

At 9 PM, the temperature is −8°C, the temperature at 12 midnight will be =

(−8°C)+(−2°C×3hours)

=(−8°C)+(−6°C)

=−14°C

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