In: Statistics and Probability
The table lists heights (in.) of fathers and the heights (in.) of their first sons.
Height of father (x) |
73.0 |
75.5 |
75.0 |
75.0 |
75.0 |
74.0 |
74.0 |
73.0 |
73.0 |
78.5 |
Height of first son (y) |
74.0 |
73.5 |
71.0 |
70.5 |
72.0 |
76.5 |
74.0 |
71.0 |
72.0 |
73.2 |
Solution:
X | Y | XY | X^2 | Y^2 |
73 | 74 | 5402 | 5329 | 5476 |
75.5 | 73.5 | 5549.25 | 5700.25 | 5402.25 |
75 | 71 | 5325 | 5625 | 5041 |
75 | 70.5 | 5287.5 | 5625 | 4970.25 |
75 | 72 | 5400 | 5625 | 5184 |
74 | 76.5 | 5661 | 5476 | 5852.25 |
74 | 74 | 5476 | 5476 | 5476 |
73 | 71 | 5183 | 5329 | 5041 |
73 | 72 | 5256 | 5329 | 5184 |
78.5 | 73.2 | 5746.2 | 6162.25 | 5358.24 |
n | 10 |
sum(XY) | 54285.95 |
sum(X) | 746.00 |
sum(Y) | 727.70 |
sum(X^2) | 55676.50 |
sum(Y^2) | 52984.99 |
Numerator | -4.70 |
Denominator | 274.50 |
r | -0.0171 |
r square | 0.0003 |
Xbar(mean) | 74.6000 |
Ybar(mean) | 72.7700 |
SD(X) | 0.8375 |
SD(Y) | 2.0293 |
b | -0.0189 |
a | 74.1781 |
a)
r = -0.0171
The linear correlation coefficient r = -0.0171
b)
b = -0.0189
a = 74.1781
So , the equation of the regression line is
= a + bx
= 74.1781 + (-0.0189)x
Put x = 77 in this equation.
= 74.1781 + [(-0.0189)* 77]
= 72.7228 inches