Question

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour after the time that she first checked her outdoor thermometer. By 6 a.m., the temperature had fallen 21 degrees. Which expression can you use to find how many hours earlier she had first checked the thermometer?

Answer 1

-21 divided by -1.4

Explanation:

I took the test and I checked my answers. It said that "A" or -21 divided by -1.4 was the correct answer

Answer 2

The expression to find how many hours earlier Sanya had first checked the thermometer is:
`(21)/(1.4)`.

Explanation:

The rate at which the temperature was falling is, 1.4 degrees per hour.

Sanya checked the temperature at 6:00 AM and found out that the temperature had fallen 21 degrees.

Compute the number of hours it took for the temperature to fall to 21 degrees as follows:

`\text{Number of hours}=\frac{\text{Final Temperature}}{\text{Rate of decrease}}`

`=(21)/(1.4)\\\\=15`

It took 15 hours for the temperature to fall to 21 degrees.

Then 15 hours before 6:00 AM is, 3:00 PM.

Thus, the expression to find how many hours earlier Sanya had first checked the thermometer is:
`(21)/(1.4)`.