Remember, the mean is the average. To find the average of a data set, add the numbers together, then divide by the number of options.
Since there was 4 people here, think about this:
Add the three people's results together.
6+5+4=15
Now, what number, when divided by 4 (because 4 people), gets 4 (for the mean)?
16
16-15=1
So, Hannah blew 1 bubble.
