1. A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is = 5. At 95% confidence, what is the margin of error?

A. 1.55 B. 25 C. 1.96 D. 26.55

2. The starting salaries of individuals with a BIT degree are normally distributed with a mean of $62,000 and a standard deviation of $8,000. What is the probability that a randomly selected individual with a BIT degree will get a starting salary of at least $50,000?

A. 0.9332 B. 0.5000 C. 0.0228 D. 0.0668

3. How many simple random samples of size 7 can be selected from a population of size 12?

A. 410 B. 618 C. 792 D. 526

4. The 75th percentile is referred to as the

B. first quartile C. second quartile D. third quartile E. fourth quartile

5. From a population with a variance of 784, a sample of 275 items is selected. At 95% confidence, the margin of error is

A. 1.25 B. 2.45 C. 3.31 D. 4.22

6. A population has a mean of 75 and a standard deviation of 8. A random sample of 800 is selected. The expected value of is

A. 8 B. 75 C. 800 D. None of these alternatives is correct.

7. A population has a mean of 80 and a standard deviation of 10. A sample of 49 observations will be taken. The probability that the sample mean will be larger than 82 is

A. 0.5228 B. 0.0808 C. 0.9192 D. 0.0228

8. A sample of 200 elements from a population with a known standard deviation is selected. For an interval estimation of the population mean, the proper distribution to use is the A. normal distribution B. t distribution with 200 degrees of freedom C. t distribution with 201 degrees of freedom D. t distribution with 202 degrees of freedom

9. The t value for a 90% confidence interval estimation with 28 degrees of freedom is

A. 1.711 B. 2.064 C. 1.703 D. 2.069

10. It is known that the variance of a population equals 1,600. A random sample of 256 has been taken from the population. There is a .95 probability that the sample mean will provide a margin of error of

A. 7.84 B. 4.90 C. 3.64 D. 1.45

11. Assume a team of researchers selected a sample from a population and the margin of error found to be 2.744 in 95% confidence level. What the sample size if the population standard deviation is 12.6.

A. 110 B. 81 C. 216 D. 217

12. If the coefficient of correlation is 0.8, the percentage of variation in the dependent variable explained by the variation in the independent variable is

A. 0.80% B. 80% C. 0.64% D. 64%

13. Regression analysis was applied between sales (Y in $1,000) and advertising (X in $100), and the following estimated regression equation was obtained. Y = 80 + 6.2 X Based on the above estimated regression line, if advertising is $10,000, then the point estimate for sales (in dollars) is A. $62,080 B. $142,000 C. $700 D. $700,000 14. If P (A) = 0.62, P(B) = 0.38, and P (A B) = 0.82, then P (A B) =

A. zero B. 0.47 C. 0.22 D. 0.40

15. The process of capturing, storing, and maintaining data is known as A. data manipulation B. data monitoring C. data warehousing D. category analysis 16. The number of electrical outages in a city varies from day to day. Assume that the number of electrical outages (x) in the city has the following probability distribution. x f(x) 0 0.80 1 0.15 2 0.05 The standard deviation for the number of electrical outages is

A. 5.77 B. 0.536 C. 0.01 D. 0.80

17. On a street, the houses are numbered from 300 to 450. The house numbers are examples of

A. categorical data B. quantitative data C. both quantitative and categorical data D. neither quantitative nor categorical data

18. A population has a mean of 200 and a standard deviation of 12. A sample of size 144 will be taken and the sample mean xwill be used to estimate the population mean. What is the expected value of x?

A. 250 B. 320 C. 200 D. 450

19. A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is = 5. What is the standard error of the mean, x? A. 0.79 B. 0.25 C. 0.45 D. 0.87

20. Given that Z is a standard normal random variable, what is the value of Z if the area to the right of Z is 0.5?

A. 0.0000 B. 1.0000 C. 0.1915 D. 0.3413

Extended Questions 1. The Reserve Bank of Australia (RBA) reports that the current average savings of a middle-class family in Australia and it is continuously decreasing over the last ten years. A team of research students surveyed 30 middle-class families recently in Australia and found that the current average savings of a family is $9,800 and the sample standard deviation is $400.

a. What is the standard error of this sample?

b. What is the margin of error at a 95% confidence level?

c. Construct a 90% confidence interval for the current mean savings of a middle-class Australian family.

d. What is the probability that the mean savings of a random sample of 40 families (from the same population) will have more than $11,500 of savings if the population mean is $10,000 and standard deviation is $3750?

2. Assume, recently TESQA surveyed a sample of 50 private higher education providers and found that the average attrition rate is 20.25% and you are planning to test the above hypotheses.

a) Formulate the appropriate hypotheses.

b) What is the value of the test statistic if the population standard deviation is 6.25%?

c) What is the p-value?

d) At =.05, what is your conclusion?