Question

the temperature at 12 noon was 10 degree Celsius above 0 if degrees at the rate of 2 degree Celsius for our until midnight at what time would the temperature be degree Celsius below zero what would be the temperature at midnight

Answer 1

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

Temperature at noon = 10°C

required temperature = 8°C below zero

In other words = -8°C

Therefore, total decrease in temperature = 10°C - (-8°C)

= 18°C

As the temperature is decreasing at the rate of 2°C per hour,

therefore required time = 18÷2 hours

= 9 hours

Therefore the time at 9 hours passed passed noon = 9 p.m.

Total decrease in temperature until mid night = 12×2°C

= 24°C

Therefore, the temperature at mid night = 10°C - 24°C

= -14°C