Recall the small bookstore.
Number of Salespeople .... Working Sales (in $1000’s)
2 ............. 10
3 ............. 11
7 ............. 13
9 ............. 14
10 ............. 18
10 ............. 20
12 ............. 20
15 ............. 22
16 ............. 22
20 ............. 26
x̄ = 10.4 .......... y-bar = 17.6
SD(x) = 5.64 ........ SD(y) = 5.34
The regression line is:
Sales = 8.10 + 0.9134 Number of Sales People Working
And the assumptions and conditions for regression are met. Calculations with technology find that
se = 1.477.
a) Find the predicted sales on a day with 500 employees working.
b) Find a 95% prediction interval for the sales on a day with 500 employees working.
c) Are these predictions likely to be useful? Explain.