STAT200 Week7 complete solutions correct answers key

STAT200 Week7 complete solutions correct answers key

DIS

Stat 200 is a required course for an undergraduate degree.  Of 9867 students taking this course in one year, 6547 passed with a grade of “C” or better.

In an ENMT majors’ course, 2375 took it in one year and 1750 passed with a grade of “C” or better.

At the 1% significance level, do the data suggest that a higher proportion of students pass the Statistics course than the proportion who pass their Major ENMT course?  EXPLAIN and SHOW your work.

TPRO

On the WEB look up the average weights of a nickel, dime and quarter.  These weights will be the INDEPENDENT VARIABLE.  Now, what is the mean (population) toss distance from the wall for these three coins?  Those are the DEPENDENT VARIABLES.  You now have just 3 pairs of values.  Make a scatter diagram of these three data points (weight, distance).  Does the plot look linear?  Calculate the equation for the best fit regression line.  What is the correlation coefficient?  What is your conclusion about the linearity or correlation of weight verses distance based on our coin toss data?

HW

1.     What is the equation for a regression line? What does each term in the line refer to?

4. What does the standard error of the estimate measure? What is the formula for the standard error of the estimate?

6. For the X,Y data below, compute: a. r and determine if it is significantly different from zero. b. the slope of the regression line and test if it differs significantly from zero. c. the 95% confidence interval for the slope.

X/Y

4/6

3/7

5/12

11/17

10/9

14/21

7. What assumptions are needed to calculate the various inferential statistics of linear regression?

14. True/false: If the slope of a simple linear regression line is statistically significant, then the correlation will also always be significant

15. True/false: If the slope of the relationship between X an Y is larger for Population 1 than for Population 2, the correlation will necessarily be larger in Population 1 than in Population 2. Why or why not?

16. True/false: If the correlation is .8, then 40% of the variance is explained

17. True/false: If the actual Y score was 31, but the predicted score was 28, then the error of prediction is 3.

CH17

5. At a school pep rally, a group of sophomore students organized a free raffle for prizes. They claim that they put the names of all of the students in the school in the basket and that they randomly drew 36 names out of this basket. Of the prize winners, 6 were freshmen, 14 were sophomores, 9 were juniors, and 7 were seniors. The results do not seem that random to you. You think it is a little fishy that sophomores organized the raffle and also won the most prizes. Your school is composed of 30% freshmen, 25% sophomores, 25% juniors, and 20% seniors.

A. What are the expected frequencies of winners from each class?

B. Conduct a significance test to determine whether the winners of the prizes were distributed throughout the classes as would be expected based on the percentage of students in each group. Report your Chi Square and p values

C. What do you conclude

ILL CH-11

8. A personal trainer is putting together a weight-lifting program for her clients. For a 90-day program, she expects each client to lift a specific maximum weight each week. As she goes along, she records the actual maximum weights her clients lifted. She wants to know how well her expectations met with what was observed. Use the following information to answer the next five exercises: A teacher predicts that the distribution of grades on the final exam will be and they are recorded in Table 11.27.

11.27 GRAPH

Grade/ Proportion

A/ 0.25

B/ 0.30

C/ 0.35

D/ 0.10

11.28 GRAPH

Grade /Frequency

A/ 7

B /7

C /5

D/ 1

9. d f =

10. State the null and alternative hypotheses.

11. χ 2 test statistic =

12. p-value =

13. At the 5% significance level, what can you conclude?

102. Do men and women select different breakfasts? The breakfasts ordered by randomly selected men and women at a popular breakfast place is shown in Table 11.55. Conduct a test for homogeneity at a 5% level of significance.

French/ Toast /Pancakes/ Waffles /Omelettes

Men-- 47 35 28 53

Women-- 65 59 55 60