CIMA BA1 · Chapter 11 · Question 3 of 11
Five pairs of observations give: sum of x = 15, sum of y = 27, sum of xy = 93, sum of x squared = 55, n = 5. What is the least squares regression line of y on x?
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: D) y = 1.8 + 1.2x
Explanation
b = (n x sum xy - sum x x sum y) / (n x sum x squared - (sum x) squared) = (5 x 93 - 15 x 27) / (5 x 55 - 15 x 15) = (465 - 405) / (275 - 225) = 60 / 50 = 1.2. a = mean of y - b x mean of x = 27/5 - 1.2 x 15/5 = 5.4 - 3.6 = 1.8. So y = 1.8 + 1.2x.
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