How close is the theoretical distribution for the middle five columns? These columns are less than 3 up and down from the theoretical mean (13). Because the theoretical standard deviation is 2.55, these five bins encompass about standard deviation. Use the counters at the top of each column to find the number of balls in each of the five central columns and enter your values in the table. Add these five values and enter the sum in the Total column. How closely does this total match the theoretical percentage of balls that you would expect to land in this area ( standard deviation from the mean)?