Twenty lab rats are taught to push a lever in their cage to drop a food pellet. For 10 days, the rats learn to push the lever and, each time, a food pellet drops. On the 11th day, the researchers remove the food pellets, but keep the lever in the cage. The number of times each rat pushes the lever on the 11th day is recorded for each rat and displayed in the histogram below. Frequency of Pushes 10 8 6 2 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Pushes Calculate the mean for the number of pushes on the 11th day. (Do not round.)