Please give reasonings behind choices trying to learn!!!!!

Which is a characteristic of a histograms bars?

A.The bar widths reveal the cumulative frequencies of data values.

B. The bar widths indicate class intervals, and their areas indicate frequencies.

C. The bar widths show class intervals, and their heights indicate frequencies.

D. The bar widths are an exact multiple of the sample size.

Which of the following is NOT true?

A. The second quartile is the same as the median.

B. It is inappropriate to apply the Empirical Rule to a population that is right-

skewed.

C. Chebyshevs Theorem says that at least 75 percent of the data lie within 2

standard deviations of the mean.

D. When data are right-skewed, we expect the median to be greater than the

mean.

The heights of male students in a certain statistics class range from Xmin = 61 to Xmax = 79. Applying the Empirical Rule, a reasonable estimate of would be

a. 2.75

b. 3.00

c. 3.25

d. 3.50

A machine dispenses water into a glass. Assuming that the amount of water dispensed follows a continuous uniform distribution from 10 ounces to 16 ounces, what is the probability that 13 or more ounces will be dispensed in a given glass?

a. 0.1666

b. 0.3333

c. 0.5000

d. 0.6666

Which is the correct Excel formula for the 80th percentile of a distribution that is N(475, 33)?

A. = NORM.DIST(80, 475, 33, 1)

B. = NORM.INV(0.80, 475, 33)

C. = NORM.S.INV((80 475)/33)

D. = NORM.DIST(80, 475, 33, 0)

Which of the following statements is most nearly correct, other things being equal?

A. Using Students t instead of z makes a confidence interval narrower.

B. The table values of z and t are about the same when the mean is large.

C. For a given confidence level, the z value is always smaller than the t value.

D. Students t is rarely used because it is more conservative to use z.

In a two-tailed test, a statistician got a z test statistic of 1.82. What is the p-value?

a. .0708

b. .0688

c. .0874

d. .0301

Which of the following is true?

A. A two-tailed hypothesis test for H0: = 15 at = .10 is analogous to asking if

a 90 percent confidence interval for contains 15.

B. For a given level of significance, the critical value of Students t increases

as n increases.

C. For a given H0 and level of significance, if you reject the H0 for a one-tailed

test, you would also reject H0 for a two-tailed test.

D. For a given sample size, reducing the level of significance will decrease the

probability of making a Type II error.

If the attendance at a baseball game is to be predicted by the equation Attendance = 16,500 75 Temperature, what would be the predicted attendance if Temperature is 90 degrees?

A. 6,750

B. 9,750

C. 12,250

D. 10, 020

In a sample of n = 23, the critical value of Students t for a two-tailed test of significance for a simple bivariate regression at = .05 is

a. 2.229

b. 2.819

c. 2.646

d. 2.080

A fitted regression Profit = 262 + 1.51 Sales (all variables in thousands of dollars) was estimated from a random sample of 15 small coffee kiosks. We can say that

A. the slope is too small to be significant.

B. the intercept does not seem reasonable.

C. the R2 will be low due to small sample size.

D. predictions are likely to be underestimated.

12.The unexplained sum of squares measures variation in the dependent variable Y about the

A. mean of the Y values.

B. estimated Y values.

C. mean of the X values.

D. Y-intercept.

13. Which is a characteristic of the variance inflation factor (VIF)?

A. It is insignificant unless the corresponding t statistic is significant.

B. It reveals collinearity rather than multicollinearity.

C. It measures the degree of significance of each predictor.

D. It indicates the predictors degree of multicollinearity.

Which of the following would be most useful in checking the normality assumption of the errors in a regression model?

A. The t statistics for the coefficients.

B. The F-statistic from the ANOVA table.

C. The histogram of residuals.

D. The VIF statistics for the predictors.

The owner of Torpid Oaks B&B wanted to know the average distance its guests had traveled. A random sample of 16 guests showed a mean distance of 85 miles with a standard deviation of 32 miles. The 90 percent confidence interval (in miles) for the mean is approximately

A. (71.0, 99.0)

B. (71.8, 98.2)

C. (74.3, 95.7)

D. (68.7, 103.2)

PART B: PROBLEMS

(Show ALL steps of your work clearly. Partial answers get partial credits.)

1. [10 points] A large number of applicants for admission to graduate study in business are given an aptitude test. Scores are normally distributed with a mean of 460 and standard deviation of 80.

a. [5points]What fraction of applicants would you expect to have scores of 600 or above?

b. [5points]What score would the top 2.5 percent of the applicants at least have?

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2. [15points]A digital camcorder repair service has set a goal not to exceed an average of 5 working days from the time the unit is brought in to the time repairs are completed. A random sample of 12 repair records showed the following repair times(indays):5,6,7,7,7,5,4,6,6,5,6,7.x= 5.9167,=0.9962.

a. [5 points] H0: 5 days versusH1:> 5 days. At the 5 percent level of significance ( = 0.05), tcrit = 1.7960. What are the decision rules?

b. [5 points] Calculate the test statistic tcalc.

c. [5 points] Is the goal being met? Please explain.

3. [30Points]Suppose we have data set that shows the following information for 400 people: Balance (average credit card debt), Income (in thousands of dollars), Limit (credit limit), Cards (number of cards a person has), Rating (credit rating), and Education (years of education of a person). In addition, there are two qualitative predictors: Gender is 1 if the person is female and 0 if the individual is male, and Student is 1 if the person is a student and 0 otherwise. We run a regression to determine the relationship between the response variable Balance and the rest of the variables. Part of the Excel output is as shown on the next page. Answer the following questions based on this output.

a. [5 points] What are the values of (1) (2) (3) (4) (5)? (Round your answer to 4 decimal places.)

b. [5points]What is the coefficient of determination for this regression? Interpret this number.

c. [5 points] Interpret the overall significance of the regression using the F test.

d. [5points]Interpret the exact meaning of the slope coefficient of Income.

e. [5points]Interpret the exact meaning of the slope coefficient of Student.

f. [5 points] Which predictors are significant at a confidence level of 95%, or equivalently, at a significance level of 5%? Explain your reasoning.