A factory manager recorded the number of hours a new machine operated each day and the number of units it produced. The scatterplot above shows this data for 10 days, along with a line of best fit. The equation of the line of best fit is approximately , where is the number of hours the machine operated and is the number of units produced. Which of the following statements is the best interpretation of the number 15 in the equation?
The machine produces an average of 15 units per day.
The machine produces 15 units when it operates for 0 hours.
For each additional hour the machine operates, the number of units produced is estimated to increase by 15.
The total number of units produced after 15 hours of operation.
