A store owner asks each person to write “Yes” or “No” on a slip of paper as they leave, secretly writing down whether they were happy with their experience. At the end of the day, the owner selects 12 slips at random and looks at them. These were the results:
yes, yes, yes, no, yes, no, yes, yes, no, yes, no, yes

a. Estimate the proportion of all shoppers who were happy with their experience that day.