Samples and Probability
I have a population of 100, mean of 500 and standard deviation of 100. I am asked what range of values should contain the sample mean 90% of the time.
I have calculated the standard error =10.
I don’t know what figure to use in the z scores tables, column d. 1/2 of 90% is 45% or .4500. My choices in column D are .4495 or .4505. Which is correct? How do I know which one to use?