A. Intervals

QUESTION 1

Find the appropriate t-distribution value for the following confidence intervals:

1. 90% confidence, n is24: Answer=

2. 95% confidence, n is16: Answer =

3. 98% confidence, n is26: Answer =

QUESTION 2

If the sample size was 14, and the t-value was 1.771, what is the correct confidence interval?

QUESTION 3

City planners would like to know the average income in Red Deer and would like to conduct a sample to collect this information. The sample data surveyed 256 households which revealed a sample mean of $85,000. The population standard deviation is known to be $13,200.

a) What is the standard error ofthemean?

b) At the 95% confidence level, what is the margin of error?

c) What is the upper limit in the interval?

d) What is the lowerlimitin the interval?

QUESTION 4

Calculate the margin of error for the following confidence intervals:

1. 99% confidence, population standard deviation is 500, n is 100. Margin of error =

2. 98% confidence, sample standard deviation is 125, n is 25. Margin of error =

Final answers rounded to the nearest whole number.

QUESTION 5

Calculate the standard of error of the mean for the following:

A sample of 81 items is selected from a population of 400 which has a standard deviation of 54. Final answer rounded to one decimal place.

Standard error = [a]

QUESTION 6

A sample of 200 students indicated that 120 preferred strawberry icecream to vanilla icecream.

1. What is the sample proportion of students who preferred strawberry icecream?

2. Calculate the standard error of the proportion. Round answer to 3 decimal places.

3. At the 90% confidence interval, calculate the margin of error. Round answer to 2 decimal places.

4. What is the upper limit in this confidence interval?

QUESTION 7

What does the 'alpha' symbol, in confidence intervals, represent?

	a.	the chance of being correct
	b.	the standard error
	c.	the chance of error
	d.	the margin of error

QUESTION 8

1. If a smaller margin of error is required, whatshould be changed?

	a.	decrease the sample size
	b.	increase the sample size
	c.	decrease the population size
	d.	increase the confidence interval

QUESTION 9

If the required margin of error is 225, and the standard deviation is 1200, what would be the appropriate sample size if the confidence interval is 95%

QUESTION 10

If the required margin of error is limited to 1.5%, what would be the appropriate sample size if the confidence interval is 98%

B. Hypothesis Testing

QUESTION 1

The average rainfall last year was at least 13.5 cm. An environmental group believes that the average rainfall has fallen. With a sample of 65 days, they found an average rainfall of 11.5 cm. Thepopulation standard deviation is known to be 5.5 cm. Testthe hypothesis that the average rainfall has decreased at the 0.05 level of significance.

Is this a one or two tail hypothesis test? (Enter "1" or "2")

QUESTION 2

Refer to the data in question 1.

Determine the critical value.

QUESTION 3

Refer to the data in question 1.

Calculate the test statistic. (round your answer to 2 decimal places)

QUESTION 4

Refer to the data in question 1.

What is your decision in regards to the Null hypothesis?

Enter "1" for Reject Ho

Enter "2" for Do not reject Ho

Enter "3" for Accept Ho

QUESTION 5

Refer to the data in question 1.

Calculate the p-value. (Round answer to 4 decimal places)

QUESTION 6

At the beginning of the 2011-2012 NHL season, executives believed that scoring had maintained the 5-year average of 4.25 goals per game. Don Cherry, however, thought that something was different with scoring. He took the first 22 games of the season and found that the average goals per game was 5.75 with a standard deviation of 1.24. Test the claim that scoring is different than the 4.25 goals per game claim at the 0.02 level of significance.

Is this a one or two tail test?

Enter "1" or "2"

QUESTION 7

Refer to the data in question 6.

Determine the critical value.

QUESTION 8

Refer to the data in question 6.

Calculate the test statistic. (Round your answer to 2 decimal places)

QUESTION 9

Refer to the data in question 6.

What is your decision in regards to the Null hypothesis?

Enter "1" forReject Ho

Enter "2" for Do not reject Ho

Enter "3" for Accept Ho

QUESTION 10

The proportion of students who have changed their major during their first year of college is believed to be 25%. Concerned faculty and staff have noticed that in the current year, the proportion is not the same and have collected data which revealed that in a sample of 150 students, 51 students changed their major. Is there enough evidence to indicate that the initial claim is now different? Test the claim at the 5% level of significance.

Is this a one or two tail test?

QUESTION 11

Refer to the data in question 10.

Determine the critical value.

QUESTION 12

Refer to the data in question 10.

Calculate the standard error.(Round your answer to 3 decimal places)

QUESTION 13

Refer to the data in question 10.

Calculate the test statistic. (Round answer to 2 decimal places and use standard error as entered in previous question)

QUESTION 14

Refer to the data in question 10.

What is your decision in regards to the Null hypothesis?

Enter "1" for Reject Ho

Enter "2" for Do not reject Ho

Enter "3" for Accept Ho

QUESTION 15

Refer to the data in question 10.

Calculate the p-value (Round answer to 4 decimal places)