Question

A textbook publisher for books used in business schools believes that the number of books sold is related to the number of campus visits to decision makers made by their sales force. A sampling of the number of sales calls made and the number of books sold is shown in the following table.

# OF SALES CALLS MADE ----- # OF BOOKS SOLD

25 375

15 250

25 525

45 825

35 550

25 575

25 550

35 575

25 400

15 400

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Sales Calls Made Versus Number of Books Sold Summary

Measure Value

Error Measures

Cummulative For. Error = 0

MAD = 72.5

MSE = 5550.986

Standard Error (denom=n=8) = 83.299

MAPE = 0.163

Regression Line

Books Sold = 104,605

+ 14.737 * Sales Calls Made

Statistics

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1. What percent in the variation of the variable Books Sold is explained by the value of the variable Sales Calls Made?

A) 86.5%

B) 83.3%

C) 74.8%

D) 72.5%

2. For every sale call made, the number of books sold increases by:

A) 14.74 books.

B) 104.6 books.

C) 83.30 books.

D) 7.25 books.

3. If a sales representative makes 55 sales calls, the number of book sales the publisher should expect is:

A) 105.

B) 4,581.

C) 114.

D) 915.

4. To realize the sale of 700 books, how many sales calls will the sales representative have to make?

A) 40.4

B) 45.9

C) 32.7

D) 37.6

Please provide explantions and/or show your work.

Answer 1

1. R²-value measures the percentage of variation in the values of the dependent variable that can be explained by the variation in the independent variable.

So, percent in the variation of the variable Books Sold is explained by the value of the variable Sales Calls Made will be measured R²

Plot the Sales Calls Made (x) and Number of Books Sold (Y) with trend line as linear

R² = 0.7483 = 74.83 %

Answer C) 74.8 %

2. For every sale call made, the number of books sold increases is slope of regression line

y = 14.737x+ 104.61

Slope = 14.737 = 14.74

Answer A ) 14.74

3. Sales Calls Made (x) and Number of Books Sold (Y)

x= 55, Putting x = 55 in linear regression equation

y = 14.737x+ 104.61 = 915.145 = 915

Answer D) 915

4.

y = 700

y = 14.737x+ 104.61 = 700

=> x = (700-104.61)/14.737 = 40.40

Answer A) 40.4