Question

The following Excel table is the result of a study by MBA students to see if the average commuting times from suburbs to down town Chicago is any different in the winter. At the .05 level of significance, can it be concluded that the commuting times are different in the winter?

                       

	Winter	Spring , Summer, Fall
Mean	38.2 minutes	32.5 minutes
Known Variance	82.81	51.84
Observations	40	40
Hypothesized Mean Difference	0	0
Z	4.50
P(Z<=z) One-tail	.004
Z Critical one-tail	1.645
P(Z<=z) Two-tail	.008
Z Critical two-tail	1.96

Answer 1

Claim: The commuting times are different in the winter.

The null and alternative hypothesis is

H0: The commuting times are the same in the winter.

H1: The commuting times are different in the winter.

Level of significance = 0.05

Our hypothesis is a two-tailed test.

P-value = 0.008 ( Using result)

P-value < 0.05 we reject null hypothesis.

Conclusion: The commuting times are different in the winter.