Quiz 1



STA 10 Quiz 2 Name:

1. The amount of spread in the data is a measure of what characteristic of a data set? B

a. Center

b. Variability

c. Shape

d. None of the above

2. Which of the following statements regarding stemplots is false? B (This question is not very good; everyone gets this point! )

a. A stemplot allows you to retrieve the original data (assuming no digits are dropped).

b. A stemplot can never reuse the same stem digit twice.

c. If a certain value in your data set is repeated three times, it must appear 3 times in appropriate stem and leaf of the stemplot.

d. None of the above statements are false.

3. Which of the following statements is true? B

a. If a data set is skewed to the right, that means there is bias in the results; the data are higher than they should be.

b. If a data set is skewed to the right, then the higher values are more spread out than the lower values.

c. If a data set is skewed to the right, then the lower values are more spread out than the higher values.

d. None of the above.

4. How do you calculate the interquartile range for a data set? B

a. Take the highest value minus the lowest value and divide it by four.

b. Subtract the value of the lower quartile from the upper quartile.

c. Subtract the value of the upper quartile from the lower quartile.

d. Divide the data set into four equal parts and find the range between each of the resulting quarters.

5. Suppose you look at two boxplots comparing the weights of male cats vs. female cats, and you find that the box for the males is much wider than the box for the females. What does this mean about the data sets? B

a. Male cats weigh more than female cats overall.

b. Male cats have more variability in their weights than female cats.

c. Weights of male cats are more skewed than for female cats.

d. None of the above.

6. What is another term for measurements following a ‘normal distribution’? D

a. The measurements follow a ‘bell-shaped curve.’

b. The measurements follow a ‘normal curve.’

c. The measurements follow a ‘Gaussian curve.’

d. All of the above

7. Which of the following describes measurements that have a normal distribution? D

a. The majority of the measurements are somewhere close to the average.

b. The farther away you move from the average, the fewer individuals will have those more extreme values for their measurements.

c. The mean of the measurements is located in the middle of the bell-shaped curve.

d. All of the above.

8. Suppose one individual in a certain population had a z-score of −2. Which of the following is true?

a. This is a bad thing because the individual is below average. B

b. This individual’s measurement is 2 standard deviations below the mean.

c. This individual’s original measurement was a negative number.

d. All of the above are true.

For Questions 9 -10 use the following narrative

Narrative: Men’s heights

Suppose the mean height for adult males in the U.S. is about 70 inches and the standard deviation is about 3 inches. Assume men’s heights follow a normal curve.

(The Empirical Rule says that for a normal curve, approximately 68% of the values fall within 1 standard deviation of the mean in either direction, while 95% of the values fall within 2 standard deviations of the mean in either direction.)

9. {Men’s heights narrative} Using the Empirical Rule, 95% of adult males should fall into what height range? A

a. They should be between 64 and 76 inches tall.

b. They should be close to the height that is 95% of the mean. That is, 66.5 inches, plus or minus 2 standard deviations.

c. They should be at or below the 95th percentile, which is 74.92 inches.

d. None of the above.

10. {Men’s heights narrative} What do you need to check for first, before using the Empirical Rule to describe a population? C

a. You need to check whether or not the population is large.

b. You need to check whether or not the population is Empirical.

c. You need to check whether or not the population follows a bell-shaped curve.

d. None of the above. The Empirical Rule works for any population.

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