Answer:
Test statistic is -1.8975
The mean number of days until a home is sold is not different than the Hamilton county mean of 86 days in the nearby county.
Step-by-step explanation:
Null hypothesis: The mean number of days until a home is sold in the nearby county is the same as Hamilton county.
Alternate hypothesis: The mean number of days until a home is sold in the nearby county is different from Hamilton county.
Z = (sample mean - population mean) ÷ sd/√n
sample mean = 80 days
population mean = 86 days
sd = 20 days
n = 40
Z = (80 - 86) ÷ 20/√40 = -6 ÷ 3.162 = -1.8975
Assuming a 0.05 significance level, the critical value for a two-tailed test lies between -1.96 and 1.96
Conclusion: Since the test statistic -1.8975 falls within the region bounded by -1.96 and 1.96, fail to reject the null hypothesis