The housing market in my area has seen a 12% trend downward in the average price.
Further, the time to closing appears to have taken more time as compared to 3 years ago.
Here are the values for the average time to close for the houses in the area.
Mean = 22.3 weeks STD deviation = 5.5
Sampling 30 houses would you expect the time to close to be 24 weeks?
Why or why not?
Z = (mean1 - mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√(n-1)
Since 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 related to the Z score.