An equation was used to predict possible sales of phones for six months. The actual sales of phones are also listed.
Actual sales 55 150 325 510 780 990
Predicted sales 40 150 300 500 800 1,000
What is the sum of the residuals?
The residuals can be calculated by subtracting the predicted sales from the actual sales.
Residuals for each month:
55 - 40 = 15
150 - 150 = 0
325 - 300 = 25
510 - 500 = 10
780 - 800 = -20
990 - 1,000 = -10
Adding up the residuals: 15 + 0 + 25 + 10 - 20 - 10 = 20
The sum of the residuals is 20.