Question

in the 1980's and 1990's growth in retail sales in sporting goods stores was approximately linear. In 1982 sales were 2.3 billion. In 1988 retail sales were 41 billion. Let t=0 for 1980 What was the rate of change in sales in the 1980's Interpret

Answer 1

Since t=0 represents the year 1980. So, t=1 represents 1981  , t=2 represents 1982, t=3 represents 1983  and so on.

At t=2 that is in 1982, sales were 2.3 billion  and at t=8 that is 1988, sales were 41 billion.

So, we have the coordinates (2, 2.3) and (8, 41) The slope will give us the rate of change in sales over the years.

Therefore, Slope = $\frac{(41-2.3)}{(8-2)}$=6.45 billion per year.

Since, the rate of change is 6.45 billions per year and it is a linear variation therefore, the rate of change in sales 1980 is 6.45 billions per year.