An equation was used to predict possible sales of phones for 6 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 the sum of the residuals is numerical answers expected!

  20

Step-by-step explanation:

The sum of (actual - predicted) is ...

  {55, 150, 325, 510, 780, 990} - {40, 150, 300, 500, 800, 1,000}

  = total({15, 0, 25, 10, -20, -10}) = 20

The sum of residuals is 20.

the revenue of the fitness center, y, is the product of two factors: the number of members and the fee paid by each member. there are 320 members now, but number of members goes down by 10 for each $5 increase in fees, so if x is the number of $5 price increases then members is equal to (320 - 10x). since the fee is currently $45, and the fee increases by $5 for every price bump x, the fee is given by (45 + 5x). so, revenue y is given by y = (320 - 10x)(45 + 5x).