Using a 90% confidence level, calculate the confidence intervals.

1) 2 points. Find the mean , of your sample.
2) 2 points. Calculate the standard deviation, s, of your sample.

3) 2 points. Use Table A-3 to look up your critical value,
.

4) 2 points. Calculate margin of error

5) 2 points. Calculate lower limit of your interval, formula: .

6) 2 points. Calculate upper limit of your interval, formula: .

7) 2 points. Interpret the results