STAT 230 Summer 2014 Final_Exam

Use the information below to answer Questions 1 through 3.

Given a sample size of 34, with sample mean 660.3 and sample standard deviation 104.9, we perform the following hypothesis test. Since n>30, this is a Z test.

Null Hypothesis0 :700 H 

Alternative Hypothesis:700 a H 

1. What is the test statistic? What is the p-value?

2. At a 5% significance level (95% confidence level), what is the critical value(s)in this test? Do we reject the null hypothesis?

3. What are the border values of between acceptance and rejection of this hypothesis?x

Questions 4 through 7 involve rolling of dice.
4. Given a fair, six-sided die, what is the probability of rolling the die twice and getting a "1" each time?
5. What is the probability of getting a "1" on the second roll when you get a "1" on the first roll?
6. The House managed to load the die in such a way that the faces "2" and "4" show up twice as frequently as all other faces. Meanwhile, all the other faces still show up with equal frequency. What is the probability of getting a "5" when rolling this loaded die?
7. Write the probability distribution for this loaded die, showing each outcome and its probability.
 

Use the data in the table to answer Questions 8 through 9.x
 
8. Determine SSxx, SSxy, and SSyy.

9. Find the equation of the regression line. What is the predicted value when 4? x 

Use the data below to answer Questions 10 through 12.

A group of students from three universities were asked to pick their favorite college sport to attend of their choice: The results, in number of students, are listed as follows: Football
 
Basketball
 
Soccer
 

Maryland
 
60
 
70
 
20
 

Duke
 
10
 
75
 
15
 

UCLA
 
35
 
65
 
25
 

Supposed that a student is randomly selected from the group mentioned above.

10. What is the probability that the student is from UCLA or chooses football?
11. What is the probability that the student is from Duke, given that the student chooses basketball?
12. What is the probability that the student is from Maryland and chooses soccer?

Use the information below to answer Questions 13 and 15.

There are 4000 mangoes in a shipment. It is found that it a mean weight of 15 ounces with a standard deviation of 2 ounces.

13. How many mangoes have weights between 14 ounces and 16 ounces?
14. What is the probability that a randomly selected mango weighs less than 14 ounces?
15. A quality inspector randomly selected 100 mangoes from the shipment.
a. What is the probability that the 100 randomly selected mangoes have a mean weight less than 14 ounces?
b. Do you come up with the same result in Question 14? Why or why not?

16. Suppose that in a box of 20 iPhone devices, there are 5 with defective antennas. In a draw without replacement, if 3 iPhone devices are picked, what is the probability that all 3 have defective antennas?

Use the information below to answer Questions 17 and 18.
 
Benford's law, also called thefirst-digit law, states that in lists of numbers from many (but not all) real-life sources of data, the leading digit is distributed in a specific, non-uniform way shown in the following table.Leading Digit
 
1
 
2
 
3
 
4
 
5
 
6
 
7
 
8
 
9
 

Distribution of Leading Digit (%)
 
30.1
 
17.6
 
12.5
 
9.7
 
7.9
 
6.7
 
5.8
 
5.1
 
4.6

17. Suppose you are hired as a forensic accountant by the owner of this small business, what statistical test would you employ to determine if there is fraud committed in the issuing of checks? What is the test statistic in this case?

18. What is the critical value for this test at the 5% significance level (95% confidence
level)? Do the data provide sufficient evidence to conclude that there is fraud
committed?
Hypothesis Test versus Confidence Interval – Questions 19 through 21
Random samples of size n1=55 and n2 = 65 were drawn from populations 1 and 2 ,
respectively. The samples yielded