Question 1183586
try these numbers.
see if they work.
let me know how you did.
if ok, i'll send you method.


sample mean = 19.875
sample size = 16
degrees of freedom = 15
sample standard deviation = 3.6492
critical t-score with 15 degrees of freedom at 90% two tail confidence interval = plus or minus 1.753.
t-score formula is t = (x - m) / s
x is the raw score
m is the mean
s is the standard error of the sample.
standard error of the sample = 3.6492 / sqrt(16) = .9123
on the low side, -1.753 = (x - 19.875) / /.9123
solve for x to get:
x = 18.276
on the high side, 1.753 = (x - 19.875) / .9123
solve for x to get:
x = 21.474
i used an online calculator and got:
18.27569 and 21.47431.
me and the calculator agree.
see what you get.