Question

1. (15%) For Applied Management Statistics class you want to know how college students feel

about the transportation system in Barcelona.

1. What is the population in this study?
2. What type of sample would you use and why?

2. (25%) A manager of an e-commerce company would like to determine average delivery time of the products. A sample of 25 customers is taken. The average delivery time in the sample was four days. Suppose the delivery times are normally distributed with a standard deviation of 1.2 days.

1. Provide a 95 % confidence interval for the mean delivery time.
2. The manager claims that the average delivery time of their products does not exceed 3 days. Write the null and alternative hypothesis regarding to the claim of  the manager.
3. Test the manager’s claim at 95 % confidence level.
4. Write the conclusion of your result

3. (15%) For an effective parental skill study, a researcher asked: How many hours do your kids watch the television during a typical week in Barcelona? The mean of 100 Kids (ages 6-11) spend about 28 hours a week in front of the TV. Suppose the study follows a normal distribution with standard deviation 5.

1. Estimate the mean of all kids (ages 6-11) in Barcelona, using 99% confidence interval. (show all the calculations)
2. Write the conclusion of your result

4. (25%) A regression analysis has been conducted between the annual income (in 1000 euros) and the work experience (in years) of people with 0.05 significance level. The results are summarized below.

1. Define the independent and dependent variables. What can you say about the correlation between them.

2. Interpret R Square.
3. Write the regression model and interpret the coefficients.
4. Estimate the average annual income of a person who has 15 years of work experience.

Summary
Table 1.
Regression Statistics
Multiple R	0,93
R Square	0,86
Adjusted R Square	0,82
Standard Error	2,11
Observations	6
Table 2.
	df	SS	MS	F	Significance F
Regression	1	107,603	107,603	24,276	0,008
Residual	4	17,730	4,432
Total	5	125,333
Table 3.
	Coefficients	Standard Error	t stat	p value	Lower 95%	Upper 95%
Intercept	17,351	3,160	5,491	0,005	8,577	26,124
Variable X 1	1,362	0,276	4,927	0,008	0,595	2,130

Answer 1