Reading 11- LOS A (Part 1): Q2 between, border, points, values

cfaedu

2.A sample of paired points A and B is shown below. What is the covariance between the values of A and B?

Sample	A	B
1	1	2
2	4	5
3	9	7
4	11	10
5	14	12

A)   20.55.

B)   7.80.

C)   29.76.

D)   82.20.

cfaedu

The correct answer was A)

Sample	A	A-mean (A)	B	B-mean (B)	Product
1	1	–6.8	2	–5.2	35.36
2	4	–3.8	5	–2.2	8.36
3	9	1.2	7	–0.2	–0.24
4	11	3.2	10	2.8	8.96
5	14	6.2	12	4.8	29.76
mean	7.8		7.2	Sum>	82.2

Cov = 82.20 / (5 – 1) = 20.55