Section I: 36 points total (3 points each problem)
Circle the co
ect answer for the below multiple choice questions.
1 – The Central Limit Theorem is important in statistics because
A) For a large n, it says the population is approximately normal.
B) For any population, it says the sampling distribution of the sample mean is approximately normal, regardless of the sample size.
C) For a large n, it says the sampling distribution of the sample mean is approximately normal regardless of the shape of the population.
D) For any sized sample, it says the sampling distribution of the sample mean is approximately normal.
2) Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a certain year in the past. Suppose a sample of 100 major league players was taken. What was the standard e
or for the sample mean salary?
A) $0.012 million B) $0.12 million
C) $12 million D) $1,200.0 million
3) A confidence interval was used to estimate the proportion of statistics students that are female. A random sample of 72 statistics students generated the following 90% confidence interval: (0.438, XXXXXXXXXXUsing the information above, what size sample would be necessary if we wanted to estimate the true proportion to within ±0.08 using 95% confidence? == > Read page XXXXXXXXXX.
A) 105 B) 150 C) 420 D) 597
4) An economist is interest in studying the incomes of consumers in a particular country. The population standard deviation is known to be $1,000. A random sample of 50 individuals resulted in a mean income of $15,000. What total sample size would the economist need to use for a 95% confidence interval if the width of the interval should NOT be more than $100?
A) n = 1537 B) n = 385 C) n = 40 D) n = 20
5) A _____________________ is a numerical quantity computed from the data of a sample and is used in reaching a decision on whether or not to reject the null hypothesis.
A) Significance level B) Critical value C) Test statistic D) Paramete
6) A manager of the credit department for an oil company would like to determine whether the mean monthly balance of credit card holders is equal to $75. An auditor selects a random sample of 100 accounts and finds that the mean owed is $83.40 with a sample standard deviation of $ XXXXXXXXXXIf you were conduct a test to determine whether the auditor should conclude that there is evidence that the mean balance is difference from $75, which test would you use?
A) Z-test of a population mean B) Z-test of a population proportion
C) t-test of population mean D) t-test of a population proportion
7) The t-test for the mean difference between 2 related populations assumes that the
A) population sizes are equal
B) sample variances are equal
C) population of differences is approximately normal or sample sizes are large enough.
D) All of the above.
8) In testing for differences between the means of two related populations, the null hypothesis is
A) : =2 B) : = 0 C) : < 0 D) : > 0
9) A test for whether one proportion is higher than the other can be performed using the chi-square distribution
A) True B) False
10) A test for the difference between two proportions can be performed using the chi-square distribution.
A) True B) False
11) The slope () represents
A) Predict value of Y when X=0.
B) The estimate average change in Y per unit change in X.
C) The predict value of Y.
D) Variation around the line of regression.
12) The Y-intercept () represents the
A) estimated average Y when X = 0.
B) changed in estimated average Y per unit change in X.
C) predicted value of Y.
D) variation around the sample regression line.
Section II: 36 points total
Please show your works step by step
Problem 1: Find a symmetrically distributed interval around µ that will include 90% of the sample means when µ=286, σ = 12, and n = XXXXXXXXXXpoints)
Problem 2: A random sample of n=49 has = 72 and S = 7. Form a 99% confidence interval for μ. (5 points)
Problem 3: Please use 2-tails t test to solve this problem given the following conditions: n=9, α=.05, Mean µ=$270, = 276 and S = XXXXXXXXXXpoints)
Problem 4: Please use the paired difference test to solve this problem given the following conditions (5 points).
Employee #
Before (1)
After (2)
Difference Di
1
8
11
2
7
5
3
11
19
If α=.05, should we reject or accept Ho? (2 points)
Problem 5: Using the following Excel output regression analysis to answer problems 5A-5G (Please circle the co
ect answer). (14 points total, 2 points each).
5A) The regression equation is:
(A) = XXXXXXXXXX x
(B) = XXXXXXXXXXx
(C) = XXXXXXXXXXx
(D) = XXXXXXXXXX – XXXXXXXXXXx
(E) = XXXXXXXXXX – XXXXXXXXXXx
5B) this model predicts that the estimate total sales in 3 years is:
A. $16.807
B. $49,912
C. $41,703
D. $40,169
E. $59,021
5C) Which one of the statement A-E is the co
ect interpretation of R square?
A. 88.7% of sales increased of candy bar were co
ectly predicted by the model.
B. 78.39% of the candy bar sales are explained by the prices.
C. We can expect the model to co
ectly predict about 16.29% of the sales.
D. The regression line either passes through or is very close to 98.7% of the points in the scatter plot.
E. None of the above statement is co
ect.
5D) Which one of the statement A-E is the co
ect interpretation of the slope of the regression line?
A. The model predicts an increase in candy bar sales of $48.1928, on average, for each additional year.
B. The model predicts a decrease in candy bar sales of $ XXXXXXXXXXon average, for each additional year.
C. The model predicts an increase of candy bar sales of $ XXXXXXXXXXon average, for each additional year.
D. The model predicts a decrease in candy bar sales of $-3.810 on average, for each additional year.
E. None of the above statements is co
ect.
5E) Which one of the statement A-E is the co
ect interpretation of the Y-intercept?
A. There is no practical interpretation since one cannot have zero years of sales.
B. The model predicts that the annual sale is $ XXXXXXXXXXwhen their years of experience are zero.
C. The model predicts an increase of annual sale of $ XXXXXXXXXXif the price goes up by $1.
D. The model predicts an increase in annual sales of $ XXXXXXXXXXif the price goes up by $1.
E. None of the above statements is co
ect.
5F) Which one of the statement A-E is the co
ect interpretation of the Standard E
or of the Estimate?
A. $160 is the standard deviation of the years of experience.
B. 78.2% of the variation in the annual salaries is explained by the variation in the years of experience.
C. For each additional 1 year of sale, the prediction e
or increases by approximately $16.2986
D. $ XXXXXXXXXXis the standard deviation of the observed annual sale around the regression line.
E. None of the above statement is co
ect.
5G) At alpha (α) =.05, can we reject the null hypothesis that the slope of the population regression line is zero?
A. No, because alpha (α) is equal to p-value.
B. Yes, because a sample size of 6 is big enough to determine that the normality assumption has been met.
C. Yes, because the slope of the least square line is XXXXXXXXXX, and not zero.
D. Yes because p-value 0.000< .05 (α).
E. Can’t be determined from the information given.
Math 40-C1 Page 2
Simple Linear Regression Analysis
Regression Statistics
Multiple R0.8854
R Square0.7839
Adjusted R Square0.7299
Standard E
or16.2986
Observations6
ANOVA
dfSSMSFSignificance F
Regression XXXXXXXXXX XXXXXXXXXX
Residual XXXXXXXXXX
Total XXXXXXXXXX
CoefficientsStandard E
ort StatP-valueLower 95%Upper 95%Lower 95%Upper 95%
Intercept XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX01925
Price (X XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX07026