(a) Based on the data in Exercise 5 in Chap. 3, you conjecture that price is the decisive variable determining sales. Use a scatterplot to verify this hypothesis.

(b) Determine the standard deviation for price and the covariance between price and quantity of sales.

(c) Determine the strength of the linear metric association between item price and quantity of sales per country.

(d) Determine Spearman’s rank correlation coefficient.

(e) Use a scatterplot to interpret your results from (c) and (d).

Data From Exercise 5 in Chp3

You’re employed in the marketing department of an international car dealer. Your boss asks you to determine the most important factors influencing car sales. You receive the following data:

Country 1 2 3 4 5 6 7 8 9 10 Sales [in 1000 s of units] 6 4 3 5 2 2 5 1 1 1 Number of dealerships 7 5 4 6 6 3 6 9 9 9 Unit price [in 1000 s of ] 32 33 34 32 36 36 31] 39 40 39 Advertising budget [in 100,000 s of ] 45 35 25 40 32 43 56 37 23 34