Question

x y
0 9
2 8
3 6
4 5.5
7 3


Harriet uses a calculator to draw the line of best fit based on the points in the table. What is the slope of this line? Round to the nearest hundredth as needed.

(1 point)
Responses

0.89
0.89

9.14
9.14

-0.89
-0.89

-0.88
-0.88
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Answer 1

Use the least-squares slope formula m = [nΣ(xy) - Σx Σy] / [nΣ(x^2) - (Σx)^2].

For the points:
Σx = 0+2+3+4+7 = 16
Σy = 9+8+6+5.5+3 = 31.5
Σxy = 0+16+18+22+21 = 77
Σx^2 = 0+4+9+16+49 = 78
n = 5

m = [5(77) - 16(31.5)] / [5(78) - 16^2] = (385 - 504) / (390 - 256) = -119 / 134 ≈ -0.887

Rounded to the nearest hundredth: -0.89.