Question

1. Happy Harvest Bread Company needs to determine whether a new advertising campaign has increased its mean daily income. The daily income for 50 randomly selected business days prior to campaign was recorded. After the advertising campaign, the income for another 30 randomly selected days was recorded.     Let probability of making a type I error be 1%. Do these data provide sufficient evidence for the management to conclude that the mean income has changed by the advertising campaign? A summary of the results of the two samples is shown below:

   	Before Campaign	After Campaign
   Sample Mean	$5,255	$5,330
   Sample Standard Deviation	$215	$238
   Sample Size	50	30

   The appropriate null and alternative hypotheses are:

   	a.	H0: μ1 - μ2 > 0    Ha: μ1 - μ2 < 0
   	b.	H0: μ1 - μ2 > 0    Ha: μ1 - μ2  0
   	c.	H0: μ1 - μ2 < 0    Ha: μ1 - μ2 > 0
   	d.	H0: μ1 - μ2 = 0    Ha: μ1 - μ2 < 0

3 points   

QUESTION 17

1. The significance level of the test is:

   		.01
   		.02
   		.025
   		.005

2 points   

QUESTION 18

1. If we need to make an inference about the difference between the two population means, the appropriate test-statistic has a

   	a.	normal distribution.
   	b.	Z distribution.
   	c.	Z which can be approximated with a t distribution with 50 degrees-of-freedom.
   	d.	t distribution with 78 degrees-of-freedom which can be approximated with a Z.

4 points   

QUESTION 19

1. Calculated value of test statistic for the difference between the two population means is

   	a.	-4.94
   	b.	2.32
   	c.	-1.41
   	d.	0.186

3 points   

QUESTION 20

1. The critical value for the test statistic is:

   	a.	1.645
   	b.	1.96
   	c.	2.326
   	d.	2.576

2 points   

QUESTION 21

1. The conclusion that can be reached about the difference between the two mean incomes before and after campaign is:

   	a.	The mean income before campaign is higher than the mean income after campaign.
   	b.	The mean income before campaign is lower than the mean income after campaign.
   	c.	The mean income before campaign is the same as the mean income after campaign.
   	d.	There is a difference, the alternative hypothesis is not rejected.

Answer 1