What do you do when you are told to find the critical value and you are given conference interval and n but the population standard deviation is unknown?
I need help with:
98%, n=17, population standard deviation is unknown
90%,n=199, population standard deviation is unknown, population appears to be normal.
All you need is to decide what test-statistic is to be used then look up the critical value in a table. In your problem I'd be considering the t-statistic for the appropriate degrees of freedom .......
Eg. In the first one, so you need the value of for 16 degrees of freedom etc.