5 Questions

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Questions and Answers

- 1.The following boxplots summarize two data sets, X and Y. Which of the following must be true?
- A.
Set X and set Y have the same number of data points.

- B.
The shaded box of set X contains more data points than the shaded box of set Y.

- C.
The data set X have a larger range than the data in set Y.

- D.
About 50% of the values in set X are greater than about 75% of the values in set Y.

- E.
The median of set X is less than the median of set Y.

- 2.Two measures, x and y, are taken on numerous subjects, and a least squares regression equation is computed. The resulting equation is predicted y = 382.1 - 12.25x. A correct interpretation for the slope and intercept is:
- A.
For every increase of 100 units in x, y increases approximately 1225 units; when x = 0, y is predicted to be 382.1.

- B.
For every increase of 100 units in x, y decreases approximately 1225 units; when x = 0, y is predicted to be 382.1.

- C.
For every increase of 100 units in x, y increases approximately 32,810 units; when x = 0, y is predicted to be 12.25.

- D.
For every increase of 100 units in x, y decreases approximately 1225 units; when x = 0, y is predicted to be 12.25.

- E.
For every increase of 100 units in x, y increases approximately 1225 units; when x = 0, y is predicted to be -12.25.

- 3.Which of the following sampling designs does not contain a source of bias?
- A.
A politician would like to know how her constituents feel about a particular issue. As a result, her office mails questionnaires about the issue to a random sample of adults in her political district.

- B.
A company uses the telephone directory to randomly select adults for a telephone survey to gauge their feelings toward items manufactured by the company.

- C.
An interviewer selects a random sample of individuals to question about a particular issue. Since some of the individuals are not informed about the issue, the interviewer gives background and his personal view on the issue before recording their responses.

- D.
A news show asks viewers to call a toll-free number to express their opinions about a recent high-publicity trial.

- E.
One thousand numbered tickets are sold as a fund-raiser. Five numbers are chosen randomly, and the individuals with the winning ticket numbers each win $10.

- 4.A class of statistics students scored the following grades on a ten point quiz: 5, 2, 4, 6, 7, 9, 8, 10, 10, 6, 7, 7, 10, 4, 2. Their teacher, who sets a passing grade at 70%, looks at the distribution and see that it is
- A.
Skewed right with about 50% of the class passing.

- B.
Skewed left with about 50% of the class passing.

- C.
Skewed right with about 50% of the class failing.

- D.
Nearly symmetric with one outlier.

- E.
Nearly symmetric with no outliers.

- 5.Suppose that 25% of horses live over 23.4 years, while 85% live less than 25.2 years. Assuming the ages of horses are normally distributed, what are the mean and standard deviation for the life expectancy of horses?
- A.
20.14 and 4.86

- B.
22.69 and 1.052

- C.
22.69 and 4.97

- D.
24.11 and 1.052

- E.
Not enough information is given to find the mean and s.d.