Question 1183724
sample size is 70.
sample mean is 60.
sample standard deviation is 5.
use of t-score is indicated.
degrees of freedom is 69 (70 minus 1).
standard error is 5 / sqrt(70) = .5976 rounded to 4 decimal places.


at 80% confidence interval, alpha is .20/2 = .10.
t-score for that, with 69 degrees of freedom, is plus or minus t = 1.294, rounded to 3 decimal places.
raw score for that is 59.23 to 60.77.


at 85% confidence interval, alpha is .15/2 = .075.
t-score for that, with 69 degrees of freedom, is plus or minus t = 1.456, founded to 3 decimal places.
raw score for that is  59.13 to 60.87.


at 99.9% confidence interval, alpha is .01/2 = .005.
t-score for that, with 69 degrees of freedom, is plus of minus t = 2.649, rounded to 3 decimal places.
raw score for that is 58.42 to 61.58.


i used the ti-84 plus calculator.