Six sales representatives made the following numbers of calls to potential customers: 7, 6, 8, 6, 1, 2, with corresponding sales turnovers ($1000): 11, 10, 14, 12, 8, 9. What is the product moment correlation coefficient between number of calls and sales turnover, to 2 decimal places?

Model answer

0.88

Also accepted: 0.884

Explanation: With Sxx=40, Syy=23.33 and Sxy=27, r = Sxy/sqrt(Sxx*Syy) = 27/sqrt(40x23.33) = 27/30.55 = 0.88.

Derived from ZIMSEC Statistics Paper 1, November 2018, Q14

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