Question

The swimming pool is open when the high temperature is higher than 20^\circ\text{C}20 ? C. Lainey tried to swim on Monday and Thursday (which was 33 days later). The pool was open on Monday, but it was closed on Thursday. The high temperature was 30^\circ\text{C}30 ? C on Monday, but decreased at a constant rate in the next 33 days. Write an inequality to determine the rate of temperature decrease in degrees Celsius per day, dd, from Monday to Thursday.

Answer 1

`30-3d\leq 20`

Explanation:

Let d represent the rate of temperature decrease in degrees Celsius per day from Monday to Thursday.

As temperature decreased at a constant rate in the next 3 days, so the rate of temperature will decrease 3d degree Celsius in 3 days.

We are told that the pool was open on Monday. The high temperature was
`30^oC` on Monday. So the decrease in temperature from Monday to Thursday will be
`30-3d`.

We have been given that the swimming pool is open when the high temperature is higher than
`20^oC`.

As the pool was closed on Thursday. This means that temperature on Thursday was less than or equal to 20 degree Celsius. We can represent this information in an inequality as:

`30-3d\leq 20`

Therefore, the inequality
`30-3d\leq 20` can be used to determine the rate of temperature decrease in degrees Celsius per day, d, from Monday to Thursday.