Question

every year somerville has a citywide relay and reports the winning times. winning relay times according to the graph, when was the rate of decrease greater? between 2014 and 2015 between 2016 and 2017

Explanation:

Step1: Calculate rate of decrease for 2014 - 2015

The winning - time in 2014 is 36 minutes and in 2015 is 20 minutes. The change in time $\Delta t_1=36 - 20=16$ minutes. The rate of decrease $r_1=\frac{36 - 20}{1}=16$ minutes per year.

Step2: Calculate rate of decrease for 2016 - 2017

The winning - time in 2016 is 32 minutes and in 2017 is 28 minutes. The change in time $\Delta t_2=32 - 28 = 4$ minutes. The rate of decrease $r_2=\frac{32 - 28}{1}=4$ minutes per year.

Step3: Compare the rates

Since $16>4$, the rate of decrease is greater between 2014 and 2015.

Answer:

between 2014 and 2015