Answer:
The Standard Deviation is a measure of how spread out numbers are. You might like to read this simpler page on Standard Deviation first. But here we explain the formulas. The symbol for Standard Deviation is σ (the Greek letter sigma)
If it is less than full it means it is anything below 5/5 or 6/6, so they both have less than full water bottles...
If you meant less than half full, Josan has 0.5/5 less than half, so yes, They should stop in this case as well.
