Question

The data below represent the consumption of high- energy drinks (in gallons) by adult Americans over a nine- year period.

Year	1	2	3	4	5	6	7	8	9
Consumption (gal)	10	11	11	12	13	14	15	15	13

a. Create a time series plot to display the data.

b. Comment on the trend of consumption of high energy drinks.

c. Find the percent change from year 8 to year 9.

Answer 1

(a) here is the time series plot with x axis as Year and y axis is consumption

(b) Here as we can see that there is a significant positive and increasing trend of consumption of high energy drinks as the year progresses. But, here the trend is not montonously positive but it is progressive on the positive side.

(c) Here Consumption at year 8 = 15 gal

Consumption at year 9 = 13 gal

percent change from year 8 to year 9 = (C₉ -C₈)/C₈ * 100 = (13 - 15)/15 * 100 = -13.33%