Q: A statistics student received the following scores, each contributing a different percentage to the final grade: Quizzes: 100 (20%), Midterm Exam: 89 (30%), Student Lecture: 100 (10%), Final Exam: 92 (40%). What is the student's mean (weighted average) score?

$$\frac{100 \times 0.2 + 89 \times 0.3 + 100 \times 0.1 + 92 \times 0.4}{1} = 94.1$$

Q: If a frequency distribution has class intervals of 25-32, 33-40, 41-48, what is the formula for finding the class midpoint?

$$\text{Class Midpoint} = \frac{\text{Lower Class Limit} + \text{Upper Class Limit}}{2}$$

Question 1

A statistics student received the following scores, each contributing a different percentage to the final grade: Quizzes: 100 (20%), Midterm Exam: 89 (30%), Student Lecture: 100 (10%), Final Exam: 92 (40%). What is the student's mean (weighted average) score?

Accepted Answer

$$\frac{100 	imes 0.2 + 89 	imes 0.3 + 100 	imes 0.1 + 92 	imes 0.4}{1} = 94.1$$

Question 2

Given the LSAT scores: 174, 172, 169, 176, 169, 170, 175, what is the median score?

Accepted Answer

$$172$$

Question 3

For the LSAT scores: 174, 172, 169, 176, 169, 170, 175, what is the mode?

Accepted Answer

$$169$$

Question 4

A data set contains the following maximum numbers of passenger vehicle lanes at 16 Canadian border ports: 8, 6, 10, 3, 6, 11, 17, 2, 2, 6, 1, 10, 3, 19, 10, 5. What is the mean number of lanes?

Accepted Answer

$$\frac{8+6+10+3+6+11+17+2+2+6+1+10+3+19+10+5}{16} = 7.75$$

Question 5

Which of the following best describes why the mode may not represent the center of a data set?

Accepted Answer

The mode only reflects the most frequent value, which may be an outlier or not near the center.

Question 6

Given the data set: 40, 40, 35, 48, 38, 40, 36, 50, 32, 36, 40, 35, 30, 24, 40, 36, 40, 36, 40, 39, 33, 40, 32, 38, what is the mode?

Accepted Answer

$$40$$

Question 7

A stem-and-leaf plot is most useful for which of the following purposes?

Accepted Answer

Displaying the shape and distribution of a small to moderate set of quantitative data.

Question 8

Given the frequency distribution for Toledo, OH, average normal temperatures (°F): 25-32, 33-40, 41-48, 49-56, 57-64, 65-72, 73-80. What is the class width?

Accepted Answer

$$7$$

Question 9

For the class interval 25-32, what is the class midpoint?

Accepted Answer

$$\frac{25+32}{2} = 28.5$$

Question 10

For the class interval 25-32, what are the class boundaries?

Accepted Answer

$$24.5$$ and $$32.5$$

Question 11

A disaster area is divided into 200 equal grids. Thirty of the grids are selected, and every occupied household in the grid is interviewed. What sampling technique is used?

Accepted Answer

Cluster sampling

Question 12

Every tenth person entering a mall is asked to name his or her favorite store. What sampling technique is being used?

Accepted Answer

Systematic sampling

Question 13

Soybeans are planted on a 48-acre field divided into one-acre subplots. A sample is taken from each subplot to estimate the harvest. What sampling technique is this?

Accepted Answer

Stratified sampling

Question 14

Which of the following is a potential source of bias in the mall sampling scenario (every tenth person entering a mall is surveyed)?

Accepted Answer

People who enter the mall in groups may be over- or under-represented depending on the interval.

Question 15

A dot plot is most appropriate for which type of data?

Accepted Answer

Small sets of discrete quantitative data

Question 16

If a data set is highly skewed, which measure of center is generally preferred?

Accepted Answer

Median

Question 17

Suppose you are given a frequency distribution with class intervals of 10-19, 20-29, 30-39, and so on. If the first class has a lower class limit of 10 and an upper class limit of 19, what are the class boundaries?

Accepted Answer

$$9.5$$ and $$19.5$$

Question 18

A researcher wants to estimate the average number of hours nurses work per week. She collects data from 24 nurses and finds the following: 40, 40, 35, 48, 38, 40, 36, 50, 32, 36, 40, 35, 30, 24, 40, 36, 40, 36, 40, 39, 33, 40, 32, 38. What is the median number of hours worked?

Accepted Answer

$$38.5$$

Question 19

Which of the following is NOT a potential source of bias in cluster sampling?

Accepted Answer

Clusters are selected randomly.

Question 20

If a frequency distribution has class intervals of 25-32, 33-40, 41-48, what is the formula for finding the class midpoint?

Accepted Answer

$$	ext{Class Midpoint} = \frac{	ext{Lower Class Limit} + 	ext{Upper Class Limit}}{2}$$

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