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 for the Z score.
2. At a local university, a sample of 49 evening students was selected in order to determine whether
the average age of the evening students is significantly different from 21. The average age of the
students in the sample was 23 years. The population standard deviation is known to be 3.5 years.
Determine whether or not the average age of the evening students is significantly different from 21.
Use a 0.1 level of significance.
2 answers
a)statement of hypothesis
Null hypothesis: μ=21
Alternative hypothesis:μ ≠21
b)Test statistic value =4
c) rejection rule - reject if IzI> zα/ 2
d) zα/ 2=1.28
e)since 4 > 1.28 , reject the null hypothesis
Null hypothesis: μ=21
Alternative hypothesis:μ ≠21
b)Test statistic value =4
c) rejection rule - reject if IzI> zα/ 2
d) zα/ 2=1.28
e)since 4 > 1.28 , reject the null hypothesis