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Question
Calculate the coefficient of correlation for the ages of husbands and their respective wives:
| Age of husbands | 23 | 27 | 28 | 29 | 30 | 31 | 33 | 35 | 36 | 39 |
| Age of wives | 18 | 22 | 23 | 24 | 25 | 26 | 28 | 29 | 30 | 32 |
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Solution
Without deviation:
| Age of husbands (X) | Age of wives (Y) | X2 | Y2 | XY |
| 23 | 18 | 529 | 324 | 414 |
| 27 | 22 | 729 | 484 | 594 |
| 28 | 23 | 784 | 529 | 644 |
| 29 | 24 | 841 | 576 | 696 |
| 30 | 25 | 900 | 625 | 750 |
| 31 | 26 | 961 | 676 | 806 |
| 33 | 28 | 1089 | 784 | 924 |
| 35 | 29 | 1225 | 841 | 1015 |
| 36 | 30 | 1296 | 900 | 1080 |
| 39 | 32 | 1521 | 1024 | 1248 |
| 311 | 257 | 9875 | 6763 | 8171 |
∑X = 311, ∑Y = 257, ∑X2 = 9875, ∑Y2 = 6763, ∑XY = 8171
N = 10
Coefficient of correlation
r = `("N"sum"XY" - (sum"X")(sum"Y"))/(sqrt("N"sum"X"^2 - (sum"X")^2) sqrt ("N"sum"Y"^2 - (sum"Y")^2))`
= `(10 xx 8171 - 311 xx 257)/(sqrt (10 xx 9875 - (311)^2) sqrt(10 xx 6763 - (257)^2))`
= `(81710 - 79927)/(sqrt (98750 - 96721) sqrt (67630 - 66049))`
= `1783/(45 xx 39.76)`
= 0.9965
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