Martha constructs the table below to show the relationship between her cell phone's age and the amount of time it takes to charge her phone battery. Which of the following describes the rate at which the time to charge the phone changes?
A. The time to charge the phone increases by 25 minutes with every 7.5-month increase in the phone's age.
B. The time to charge the phone increases by 15 minutes with every 7.5-month increase in the phone's age.
C. The time to charge the phone increases by 25 minutes with every 1-month increase in the phone's age.
D. The time to charge the phone increases by 15 minutes with every 2-month increase in the phone's age.
To find the rate of increase all you have to do is take one of the data sets to see that every two months its charge time increases by 15 minutes or 7.5 minutes every month.
