# 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?

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Given: The temperature at 12 noon was 10°C above zero.

To find: Time at which the temperature would be 8°C below zero and the temperature at mid-night.

Here, the temperature 8°C below zero means -8°C.

Thus, the total drop in temperature from 10°C to -8°C would be 18°C.

As per the question, the temperature decreases at the rate of 2°C per hour. It means 2°C is decreasing in 1 hour. So, 1°C is decreasing in 1/2 hour.

Therefore, time taken to decrease the temperature by 18°C = 18/2 = 9 hours.

Now, the time at which the temperature would be 8°C below zero = 12 + 9 = 9 PM (considering the present time 12 Noon according to the question)

## Temperature at Midnight if it is 10°C above zero at 12 Noon and Decreases by 2°C Per Hour

From the above discussion it is clear that the temperature at 9 PM is -8°C.

Now, we have to determine the temperature at midnight i.e. 12 midnight.

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

The time difference between 9 PM and 12 Midnight = 12 – 9 = 3 hours.

So, the total decrease in temperature from 9 PM to 12 Midnight = -2°C x 3 = -6°C

Therefore, the temperature at midnight i.e. 12 midnight = -8°C + (-6°C) = -14°C

Summary:

## 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?

At 9 PM the temperature would be 8°C below zero if at 12 noon it was 10°C above zero and it decreases at the rate of 2°C per hour until midnight. On the other hand, the temperature at midnight would be -14°C.

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