Question

shanti wrote the predicted values for a data set using the line of best fit y = 2.55x - 3.15. she computed two of the residual values. what are the values of a and b? a = 0.4 and b = -0.15 a = -0.4 and b = 0.15 a = 8.6 and b = 14.25 a = -8.6 and b = -14.25

x	given	predicted	residual
1	-0.7	-0.6	-0.1
2	2.3	1.95	0.35
3	4.1	4.5	a
4	7.2	7.05	b

Explanation:

Step1: Recall residual formula

Residual = Given - Predicted

Step2: Calculate value of a

For $x = 3$, Given = $4.1$, Predicted = $4.5$. So $a=4.1 - 4.5=- 0.4$

Step3: Calculate value of b

For $x = 4$, Given = $7.2$, Predicted = $7.05$. So $b=7.2 - 7.05 = 0.15$

Answer:

a = -0.4 and b = 0.15