1. Here are the data from a small bookstore: Number of Salespeople Working Sales (in $1000s)...

1. Here are the data from a small bookstore:

Number of Salespeople Working	Sales (in $1000s)
2	10
3	11
7	13
9	14
10	18
10	20
12	20
15	22
16	22
20	26

a. Compute the correlation coefficient between number of salespeople and sales. Interpret the correlation coefficient. 6

b. Assuming the conditions for regression are met, find the estimated least-squares regression line and predicted sales on a day with 12 employees working. 7

c. If you expect the population regression coefficient to be positive, perform the hypothesis test of the regression coefficient at significance level of 0.05. 8

d. Find 95% prediction interval for Sales on a day with 12 employees working. 7

e. Comment on the overall quality of the fitted model using appropriate index. 7

Solutions

Expert Solution

a. Compute the correlation coefficient between number of salespeople and sales. Interpret the correlation coefficient

Sol:

the correlation coefficient between number of salespeople and sales is 0.9653.

b. Assuming the conditions for regression are met, find the estimated least-squares regression line and predicted sales on a day with 12 employees working

Sol:

The regression equaion is Y=8.1005+0.9134X

The predicted sales on a day with number of sales people working
Y=8.10+0.913(12)
=18.9

orchestra answered 1 year ago

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