Question

Confidence interval problem. Photo attached!

Answer 1

mean = 13.77, n=11, standard deviation = 1.15
do i have to incorporate the 0.5 standard deviation that was give?

Answer 2

ow my eyes!!!

Answer 3

a confidence interval uses a standard error adjustment, not a standard deviation adjustment

so yes, we need sigma

Answer 4

\[CI:=~\mu_x\pm z_{k\%}\left(\frac{\sigma}{\sqrt{n}}\right)\]

Answer 5

if sigma (population standard deviation) is known, then we use it instead of s (sample standard deviation)