BQUA 2811 XXXXXXXXXXSpring, 1996 Name _______________________________ Final Exam BQUA 2811 XXXXXXXXXXSpring, 2021 Final Exam Answer any 5 of 6 questions. Mark clearly the question that you are...

BQUA 2811 XXXXXXXXXXSpring, 1996
Name _______________________________

Final Exam
BQUA 2811
XXXXXXXXXXSpring, 2021
Final Exam
Answer any 5 of 6 questions. Mark clearly the question that you are omitting. Show all work. Partial credit will be given only for shown work. If you use Excel for any question, show what you used and what you entered to get your result. Copy any results from the screen which are pertinent to your answer. Answers without work shown will not be given full credit.
1.
A certain bank found that its checking account balances are normally distributed with mean $1,327 and standard deviation $290.
a. What percentage of balances are greater than $1,500?
b. If 2,187 accounts are greater than $1,500, approximately how many checking accounts does the bank have?
c. If it wishes to give free checking to the top 20% of account balances, what should be the minimum amount that gets free checking?
d. A sample of size 9 of balances is taken. What is the probability that the average of the sample is greater than $1,500?
2.
A sample of 49 people was taken to see how long it takes to fill out a tax return. The average of the sample was 35.5 hours. The population standard deviation is known to be 9 hours. We wish to get a 90% confidence interval on the average number of hours in the poplulaton.
a. Is it necessary to know that the population is normally distributed in order to get a confidence interval? Explain.
b. What distribution (z or t) is necessary to find this confidence interval? Why?
c. Find the margin of error.
d. Give the confidence interval.
e. What sample size would be necessary to get a confidence interval with a margin of error of 2 hours?
3.
The average time that it takes an employee to make a certain product is 45 minutes. The research department claims that a new process can reduce this time. A sample of 20 people using the new process yielded an average of 42 minutes. The standard deviation of the population is known to be 6 minutes. The company statistician devised the following hypothesis test:
Ho: µ >= 45
Ha: µ< 45
a. Find the p value for the given test. Show work.
b. With a 0.05 level of significance, will you reject the null hypothesis? Explain.
c.
Has the new technique been shown to be faster? Explain.
4.
200 students are enrolled in an Economics class. We wish to find a 95% confidence interval for the mean exam grade of all 200 students. A random sample of 5 papers was selected. The grades were 60, 75, 80, 70, and 95. The grades are assumed to be normally distributed.
a. What distribution (z or t) is necessary to find this confidence interval? Why? What is this value?
b. Find the margin of error. Show your formula.
c. Give the confidence interval.
5.
The following data set gives the number of miles traveled, the number of deliveries and travel time in hours for each of the 10 trucks’ driving assignment:
MilesDeliveriesTime
10049.3
5034.8
10048.9
10026.5
5024.2
8026.2
7537.4
6546
9037.6
9026.1
Regression Output 1
SUMMARY OUTPUT
Regression Statistics
Multiple R XXXXXXXXXX
R Square XXXXXXXXXX
Adjusted R Square XXXXXXXXXX
Standard Error XXXXXXXXXX
Observations10
ANOVA
dfSSMSFSignificance F
Regression XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
Residual XXXXXXXXXX
Total923.9
CoefficientsStandard Errort StatP-valueLower 95%Upper 95%
Intercept XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
Miles XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
Regression Output 2
SUMMARY OUTPUT
Regression Statistics
Multiple R XXXXXXXXXX
R Square XXXXXXXXXX
Adjusted R Square XXXXXXXXXX
Standard Error XXXXXXXXXX
Observations10
ANOVA
dfSSMSFSignificance F
Regression XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
Residual XXXXXXXXXX
Total923.9
CoefficientsStandard Errort StatP-valueLower 95%Upper 95%
Intercept XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
Miles XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
Deliveries XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
a. Use regression outputs 1 and 2 to determine the following:
a) Which is/are the independent variable(s)?
b) Which is/are the dependent variable(s)?
b. Use regression output 1 to answer the following questions (Justify each answer using the relevant regression statistic or statistics):
a) Is the overall model statistically significant at the .01 level of significance? .
b) Discuss the direction and strength of the relationship, if any, between miles driven and travel time.
c. In regression output 2, are each of the independent variables significant at the .01 level of significance? Justify your answer using the relevant regression statistic.
d. Which is the better model? Justify your answer using the relevant regression statistic or statistics.
e. What percentage of the variability in the dependent variable is explained by the better model?
f. Write the regression equation associated with the better model.
g. Use the better model to estimate (predict) travel time when 3 deliveries are made and 75 miles are traveled.
6. Enclosed is a file called American League. It contains the names of all the teams in the American League as well as a list of random numbers.
a. Explain clearly how the random numbers can be used to draw a random sample of six teams from the list.
b. Draw a random sample of five teams using the given random numbers. (Do not create your own random numbers.) List them in alphabetic order.
i._________________________________
ii._________________________________
iii._________________________________
iv._________________________________
v.__________________________________
7
May 13, 2021

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