Question

At midnight, the temperature in a city was 6 degrees Celsius. The temperature was dropping at a steady rate of 2 degrees Celsius per hour. A. Select the inequality that represents, x, the number of hours past midnight, when the temperature was colder than -4 degrees Celsius. Explain or show your reasoning.

Answer 1

Given:

Temperature in a city at midnight was 6 degrees Celsius.

The temperature was dropping at a steady rate of 2 degrees Celsius per hour.

To find:

The inequality that represents, x, the number of hours past midnight, when the temperature was colder than -4 degrees Celsius.

Solution:

Let x be the number of hours past midnight.

The temperature was dropping at a steady rate of 2 degrees Celsius per hour.

Total decreased temperature after x hours past midnight = 2x

So, temperature in a city after x hours past midnight = 6 - 2x

The temperature was colder than -4 degrees Celsius. It means the temperature of the city must be less than -4.

`6-2x<-4`

Therefore, the required inequality is
`6-2x<-4`.