1. Find the sample mean and sample standard deviation of your data.

2. Pick three bills from the last 12 months and change the values into z-scores. What does the z-score tell you about that particular month?

analysis

1. Between what two values would be considered a normal bill? Remember, being within 2 Standard Deviations is considered normal.

2. Are any of your bills in the last 12 months unusual? Very unusual?

3. Are there times when you would accept an "unusual" bill? Explain.

month January Februray March April May June July August September October November December mean standard deviation energy bill 14.1 14.12 14.49 14.75 15.84 22.54 36.97 51.93 72.71 104.92 115.17 129.08 N month January Februray March April May June July August September October November December mean standard deviation energy bill 14.1 14.12 14.49 14.75 15.84 22.54 36.97 51.93 72.71 104.92 115.17 129.08 N