- #1
Eclair_de_XII
- 1,083
- 91
Homework Statement
"The mean pH value of a certain chemical is to be controlled at ##\mu = 5##. Deviation from this target value in either direction is to be detected with high probability. For this purpose it is proposed to measure a ceratin number of samples from each batch and decide that the mean pH is different from 5 if the sample mean differs significantly from 5 at the 10% level of significance."
(b) "What sample size is needed if the probability of not detecting a change of one standard deviation is to be no more than 1%?"
Homework Equations
##H_0: \mu = 5##
##H_1: \mu ≠ 5##
The Attempt at a Solution
Basically, I'm interpreting this probability as the probability of a type-II error. So ##\beta = 0.01##. I know that the formula for the required sample size in this case would be: ##n=(\frac{\sigma}{E})^2##, but I don't know what ##\sigma## is. For that matter, I don't know what ##E## is supposed to be, either. So I'm kind of stuck, here.