Is sigma here standard deviation of 49 people that are randomly selected or whole population. I am also confused where sigma and sigma by root’n’ appear, when to use both of them.
sigma = 25cm , standard deviation of the population.
It made me wonder too, iff mean of population is not available then how one could go about getting std deviation.
I think the video is more about predicting mean of population from mean of sample using confidence interval.
In the later videos, namely " Unknown Standard Deviation" you can see how confidence interval is computed when std deviation of population is not known.
1 Like
Hi @AnilBhat,
I agree with you. If the population mean is not known, then the population standard deviation shouldn’t be either.