Z = (mean1 - mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√n
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.
A random sample of 50 households in community A has a
mean household income of �X
=Rs. 44,600 with a standard deviation
s =Rs. 2,200. A random sample of 50 households in community B has a
mean of �X
= Rs. 43,800 with a standard deviation of Rs. 2,800. Estimate the
di�erence in the average houshold income in the two communities using a 95
percent con�dence interval.
1 answer