Using a 90% confidence level, calculate Table A-3 (the t distribution table), if you prefer.
Steps:
1) 2 points. Find the mean, z, of your sample (not all the data, just your highlighted 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,
Remember, n is your sample size.
5) 2 points. Calculate lower limit of your interval,
6) 2 points. Calculate upper limit of your interval,
