Question

the temperature in a town increased 19°f in 3 hours. the temperature decreased 40°f in the next 6 hours. write the total change in temperature as a rate in the form of a quotient of integers. which of the following expressions shows the rate of the total change in temperature? a. $\frac{21°f}{9 hours}$ b. $\frac{59°f}{ - 9 hours}$ c. $\frac{59°f}{9 hours}$ d. $\frac{-21°f}{9 hours}$

Explanation:

Step1: Calculate total temperature change

The temperature increased by $19^{\circ}F$ and then decreased by $40^{\circ}F$. The total change in temperature is $19+( - 40)=19 - 40=-21^{\circ}F$.

Step2: Calculate total time

The first - stage time is 3 hours and the second - stage time is 6 hours. The total time is $3 + 6=9$ hours.

Step3: Find the rate of temperature change

The rate of change of temperature is the total change in temperature divided by the total time. So the rate is $\frac{-21^{\circ}F}{9\text{ hours}}$.

Answer:

D. $\frac{-21^{\circ}F}{9\text{ hours}}$