Question

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Find the value of the linear correlation coefficient r. The paired data below consist of the costs of advertising (in thousands of dollars) and the number of products sold (in thousands) 35 83 Cost 92 3 4259 10 Number 85 52 55 68 67 86 83 73 O A.-0.071 O B. 0.708 O c. 0.235 OD. 0.246

Answer 1

Answer:

	x	y	x*x	y*y	x*y
	9	85	81	7225	765
	2	52	4	2704	104
	3	55	9	3025	165
	4	68	16	4624	272
	2	67	4	4489	134
	5	86	25	7396	430
	9	83	81	6889	747
	10	73	100	5329	730
Total	44	569	320.00	41681	3347.00

Correlation coefficient

$r =\frac{\sum xy - \frac{\sum x \sum y}{n}}{\sqrt{(\sum x^2-\frac{(\sum x)^2}{n})(\sum y^2-\frac{(\sum y)^2}{n})}}$

n=8

$r =\frac{3347 - \frac{44* 569}{8}}{\sqrt{(320-\frac{(44)^2}{8})(41681-\frac{(569)^2}{8})}}$

= 217.50/ 307.3243

=0.70772145

= 0.708 ( three decimals)

Answer: B