Carla's Muffin Store is trying a promotion where store employees hand out free samples to customers on Monday afternoons. A manager at Carla's is interested in the relationship between weekly sales and the number of free samples taken by the customers.
Each week the manager records the number of free samples taken, x, and the number of muffins sold, y.
The least squares regression line of this data set is:
y=10.863x–3.899
For each free sample taken, the least squares regression line predicts that sales at Carla's will increase by ______
muffins that week.