What does the term sales rather than demand presume

Question

Assignment:

National Scan. Inc.. sells radio frequency inventory tags. Monthly sales for a seven-month period were as follows:

Month    Sales (000 units)
Feb            19
Mar            18
Apr             15
May            20
Jun             18
July             22
Aug             20

a. Plot the monthly data on a sheet of graph paper.

b. Forecast September sales volume using each of the following:

1. The naive approach.
2. A five month moving average.
3. A weighted average using .60 for August, .30 for July, and .10 for June.
4. Exponential smoothing with a smoothing constant equal to .20. assuming a a March forecast of 19(000).
5. A linear trend equation.

c. Which method seems least appropriate? Why?

d. What does use of the term sales rather than demand presume?