Chapter 14.1, Problem 57ES

a).

To determine

To find: Calculate and interpret $\frac{1}{7}{\displaystyle \sum _{i=1}^7{a}_i}$ by using the numbers from the bar graph.

b).

To determine

To find: $\frac{1}{7}{\displaystyle \sum _{i=1}^7{a}_i}$ by using the model $a_n=0.3n+3.6,n=1,\mathrm{....},7$ shows that the average number of hours per day that U.S. adult users spent on digital media $n$ year after 2010 or this underestimate or overestimate the value obtained.