DO NOT COPY & PASTE PREVIOUS ANSWERS, SHOW ALL WORK. IF HAND WRITING THE ANSWER,
ID: 3264248 • Letter: D
Question
DO NOT COPY & PASTE PREVIOUS ANSWERS, SHOW ALL WORK. IF HAND WRITING THE ANSWER, PLEASE MAKE SURE I CAN READ IT. THANKS.
The following Excel table shows the result of a study by MBA students to see if the average commuting times in the morning from southwest 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 in the morning from southwest suburbs are different in the winter?
Winter
Spring , Summer, Fall
Mean
35.2 minutes
28.5 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
DO NOT COPY & PASTE PREVIOUS ANSWERS, SHOW ALL WORK. IF HAND WRITING THE ANSWER, PLEASE MAKE SURE I CAN READ IT. THANKS.
Winter
Spring , Summer, Fall
Mean
35.2 minutes
28.5 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
Explanation / Answer
P(Z<=z) One-tail = 0.004
But this is a two tailed problem so p value = 0.004 * 2 = 0.008
Given 0.05 level of significance, p value (0.008) is less than alpha (0.05)
A small p-value (typically 0.05) indicates strong evidence against the null hypothesis, so you reject the null hypothesis.
So, we reject null that the average commuting times in the morning from southwest suburbs to down town Chicago is not different in the winter from other seasons.
So, answer is time of commuting is different.
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