Question

Customer Distribution by Weekday: A drop-in auto repair shop staffs the same number of mechanics on every weekday (weekends are not counted here). One of the mechanics thinks this is a bad idea because he suspects the number of customers is not evenly distributed across these days. For a sample of 289 customers, the counts by weekday are given in the table.

Number of Customers by Day (n = 289)

	Monday	Tuesday	Wednesday	Thursday	Friday
Count	55	68	59	67	40

The Test: Test the claim that the number of customers is not evenly distributed across the five weekdays. Test this claim at the 0.01 significance level.

(a) What is the null hypothesis for this test in terms of the probabilities of the outcomes?

H₀:  p_mon = p_tue = p_wed = p_thur = p_fri = 1/5.H₀: At least one of the probabilities doesn't equal 1/5.     H₀: None of the probabilities are equal to 1/5.H₀:  p_mon = 0.55, p_tue = 0.68, p_wed = 0.59, p_thur = 0.67, p_fri = 0.40.

(b) What is the value of the test statistic? Round to 3 decimal places unless your software automatically rounds to 2 decimal places.

χ²

=  

(c) Use software to get the P-value of the test statistic. Round to 4 decimal places unless your software automatically rounds to 3 decimal places.
P-value =  

(d) What is the conclusion regarding the null hypothesis?

reject H₀fail to reject H₀    

(e) Choose the appropriate concluding statement.

We have proven that the number of customers is evenly distributed across the five weekdays.The data supports the claim that the number of customers is not evenly distributed across the five weekdays.    There is not enough data to support the claim that the number of customers is not evenly distributed across the five weekdays.

Answer 1

a)

H0:  pmon = ptue = pwed = pthur = pfri = 1/5.H0: At least one of the probabilities doesn't equal 1/5

b)

applying chi square test:

	relative	observed	Expected		Chi square
category	frequency	Oi	Ei=total*p		R2i=(Oi-Ei)2/Ei
mon	0.200	55.000	57.800		0.136
tue	0.200	68.000	57.800		1.800
wed	0.200	59.000	57.800		0.025
thu	0.200	67.000	57.800		1.464
fri	0.200	40.000	57.800		5.482
total	1.000	289	289		8.907

χ2 =8.91

c)

p value =0.0635 (please try 0.0634 if this comes wrong)

d)

fail to reject H0    

e)

There is not enough data to support the claim that the number of customers is not evenly distributed across the five weekdays.