Question

An equation was used to predict possible sales of phones for 6 months. The actual sales of phones are also listed.

Answer 1

Answer with Step-by-step explanation:

Residual is calculated by the difference between actual value and the predicted value.

Actual sales       Predicted sales          Residual

55                        40                                15

150                       150                               0

325                      300                             25

510                       500                             10

780                       800                            -20

990                        1000                           -10

Sum of residuals=15+0+25+10-20-10

                           =20

Hence, sum of residuals is:

20

Answer 2

They were up 15+0+25+10-20-10=20. The sum was 20 :)