Question

A 2-column table with 6 rows titled Piglet Weight. Column 1 is labeled Day with entries 1, 2, 3, 4, 5, 6. Column 2 is labeled Weight (kilograms) with entries 1.2, 1.3, 1.5, 1.6, 1.9, 2.1. The table shows the number of kilograms a newborn pig weighs during its first week. What is the equation of the least-squares regression line, where is the predicted weight and x is the day? Round each coefficient or constant to the nearest hundredth. = + x

Answer 1

w = 0.18x +0.96

Explanation:

You want the equation of the best fit line for the given data of weight vs day number.

Linear regression

A suitable calculator can tell you the coefficients of the best-fit line for the given data. The attachment shows the line's equation is ...

w = 0.18x +0.96

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Additional comment

You can do the math by hand if you like. The slope of the line is the ratio of the covariance of x and w to the variance of x (covariance of x with itself). The line will pass through the point (mean(x), mean(w)), which is (3.5, 1.6). Hence the equation can be written nicely in point-slope form. The slope here is 32/175 ≈ 0.18, so the "exact" equation for the line is ...

w -1.6 = (32/175)(x -3.5)

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