The number of personal computers sold in a week by a computer for a period of 25 weeks is given as follows .

10 8 7 4 4 18 9 14 17 11 5 4 5 7 10 12 14 10 9 29 7 6 5 20 15

Find the percentage of the weeks that the weekly sales of the personal computers are within one standard deviation from the mean .

I don understand what the questino is asking .THanks for the help .