130 adults with gum disease were asked the number of times per week they used to floss before their diagnoses. The (incomplete) results are shown below:

a. Complete the table (Use 4 decimal places when applicable)

b. What is the cumulative relative frequency for flossing 6 times per week? %

250 people are asked how many siblings they have?

a. Complete the table (Use 4 decimal places when applicable)

b. What percent of the people have exactly one sibling? %

50 part-time students were asked how many courses they were taking this term. The (incomplete) results are shown below:

a. Complete the table.

b. What percent of students take exactly one course? %

50 part-time students were asked how many courses they were taking this term. The (incomplete) results are shown below:

Please fill out the table.

What percent of students take exactly two courses? %

he Gourmand Cooking School runs short cooking courses at its small campus. Management has identified two cost drivers that it uses in its budgeting and performance reports—the number of courses and the total number of students. For example, the school might run two courses in a month and have a total of 61 students enrolled in those two courses. Data concerning the company’s cost formulas appear below:

It may be that sunshine has a unique effect on learning statistics. Previous research has been in disagreement, with some studies showing that sunshine increases amount learned whereas others show sunshine has detrimental effects on learning. You would like to determine for yourself whether or not sunshine makes a DIFFERENCE on statistics learning. Let's assume you take five statistics students and give them a lesson on a sunny day, and then take a completely different and unrelated five students and give them the same lesson on a rainy day. These are their results for a quiz on their lesson:

Sunny Day Students:

• Student 1: 9.8
• Student 2: 6.7
• Student 3: 7.2
• Student 4: 8.2
• Student 5: 5.1

xbar₁ = 7.4

Rainy Day Students:

• Student 6: 8.2
• Student 7: 6.7
• Student 8: 6.8
• Student 9: 9.7
• Student 10: 7.1

xbar₂ = 7.7

a. State the null and alternative hypotheses.

b. What are the degrees of freedom for this t-test? Find the corresponding critical t-value(s) for Type I error rate (alpha) of α = 0.05?

c. Calculate your observed t-statistic (hint: you will need to calculate the standard deviations of both groups first).

d. Compare your observed t-statistic to the critical t-value. What do you conclude regarding the null hypothesis?

e. Calculate and interpret the 95% Confidence interval.

f. Calculate and interpret the standardized effect size (Cohen's d).

g. What do you conclude about your research question (use your own words, in everyday language).

A researcher tested a research hypothesis that people with diagnosed depression will have REDUCED level of depressive symptoms after a cognitive therapy treatment, as compared to the pre-treatment level of depressive symptoms. The cutoff t value is -1.833 for this one-tailed test. The data analysis yielded a mean change score (post-treatment minus pre-treatment) of -2.5. If the standard error is 2.0, what is the t statistic and what is the conclusion of the hypothesis test?

A researcher conducts a t test for dependent means (paired-samples t test) with 16 participants. The estimated population variance of the change scores is 9. What is the standard error?

In a small-scale trial (sample size = 9) of a psychotherapy treatment for depression, participants were assessed with a depression scale when they entered the trial and again when they have completed the 6-month trial. The data yielded a mean difference (change) score of 1.5 and the standard deviation of the sampling distribution was .6. What was the the t statistic?

In a high school math class, there are 13 male students and 17 female students. After all the students have taken the ACT test, the math teacher would like to know if there is a significant difference in the math component score between the male and female students. If he uses an alpha level of .05 for a two-tailed test, what would be the critical t value for his statistical test?

The Gourmand Cooking School runs short cooking courses at its small campus. Management has identified two cost drivers it uses in its budgeting and performance reports—the number of courses and the total number of students. For example, the school might run two courses in a month and have a total of 62 students enrolled in those two courses. Data concerning the company’s cost formulas appear below:

For example, administrative expenses should be $3,700 per month plus $42 per course plus $5 per student. The company’s sales should average $860 per student.

The company planned to run four courses with a total of 62 students; however, it actually ran four courses with a total of only 58 students. The actual operating results for September appear below:

Required:

Prepare a flexible budget performance report that shows both revenue and spending variances and activity variances for September. (Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance). Input all amounts as positive values.)

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The Executive Summary (excerpt)

Purpose of the Proposal

This document will acquaint the reader with 3 principle topics by

·         Showing what the San Diego State University (SDSU) Suntrakker project is;

·         Showing that the team-oriented, interdepartmental disciplines at SDSU possess the tenacity and know-how to build and race a solar-powered vehicle in the World Solar Challenge Race in Austrailia next year;

·         Define and articulate how this business team expects to promote and generate the necessary support; funds, and materials from the student body, alumni, community and local businesses to sieze and executive this opportunity.

Project Profile

The Suntrakker Solar Car project was conceived by a small group of San Diego State University engineering students motivated by the success of the General motors “Sunrayce,” committed itself to designing and building a superior solar-powered vehicle to compete in the world Solar Challenge.

From modest Beginnings, the Suntrakker project quickly revolved into a cross-disciplinary educational effort encompassing students from many colleges of San Diego State University. The project has provided students participants and volunteers with valuable real-life experiences and has brought them together in an effort that benefits not only the students and the university but also the environment.

Sponsors of this project are not only contributing to the successful achievement of the overall Suntrakker project but will also enhance their goodwill, advertising, and name promotion by association with the project. In addition, the Suntrakker offers a unique opportunity for the companies who can donate parts and accessories to showcase their name and test field their products in public in this highly publicized international contest.

?

Above data shows 13 values of the variable "distance from hometown to campus" that were provided by the students in a recent statistics class.

A. Find the mean and the median.

_____mean (round to 1 decimal place in your answer)
____median

B. Suppose the family of the student with data value 3000 moves to Tel Aviv, Israel; this changes the data value for this student from 3000 to 6000. Calculate the new mean and new median when 3000 is replaced by 6000.

_____new mean (round to 1 decimal place in your answer)
_____new median

C. Now suppose that the families of the other 5 students whose values are greater than the median also move to new locations so that each student's data value is twice as large as the original data value. (The data values of the students less than the median do not change and the 6000 data value remains at 6000). Calculate the new mean and the new median.

______new mean (round to 1 decimal place in your answer)
_____new median

D. Suppose now that the 6 students whose data values are less than the median also move to new locations so that each student's data value is half as large as the original data value. (Note that half of 0 is 0; all the data values greater than the median keep the same new values from question 3). Calculate the new mean and the new median.

_____ new mean (round to 1 decimal place in your answer)
____new median

[2 pts] Narrow confidence intervals give us more precise estimates of our parameter. What two quantities does the researcher control that affect the width of a confidence interval, and how can the researcher change them to result in narrower confidence intervals?

A random sample of 12 MSU students were surveyed and asked “How much did you spend on textbooks this semester?”

What type of plot should be used to display these data? Select all that apply.

Histogram

Segmented bar chart

Dotplot

Scatterplot

In order to create a theoretical confidence interval from these data, what must be assumed? Select one.

The sample is representative of all MSU students.

The distribution of textbook costs reported is roughly symmetric.

The students were honest in their responses.

With this sample size, we can never use theoretical methods of analysis.

[2 pts] Assume it is valid to use a theoretical confidence interval to analyze these data. The sample mean was $284.90 and the sample standard deviation was $96.10. Use these values and a multiplier of 2.201 to create a 95% confidence interval for the true mean.

[2 pts] Interpret the confidence interval in the context of the problem.

[2 pts] What is meant by having “95% confidence” in the interval?

[2 pts] If we had sampled 50 MSU students instead of 12 and gotten the same sample mean and sample standard deviation, which of the following statements would be true? Select all that apply.

The variability between individuals in our sample would decrease.

The variability between means from many samples would decrease.

The confidence interval width would decrease.

The center of the confidence interval would decrease.