Question 1

Given the following data set representing the number of newspapers sold at a shop over 10 days: 20, 23, 18, 20, 25, 20, 23, 20, 18, 20. What is the frequency of the value 20?

Accepted Answer

5

Question 2

If a data set has a largest value of 450 and a smallest value of 59, and you want to create 7 classes for a frequency distribution, what is the appropriate class width? (Round up to the next whole number.)

Accepted Answer

$$\frac{450 - 59}{7} = 56$$

Question 3

What is the formula for the midpoint (class mark) of a class interval with lower class limit $$L$$ and upper class limit $$U$$?

Accepted Answer

$$\frac{L + U}{2}$$

Question 4

A frequency distribution has the following classes and frequencies: 59–114.5 (5), 115–170.5 (8), 171–226.5 (6), 227–282.5 (2), 283–338.5 (5), 339–394 (3), 395–450.5 (1). What is the cumulative frequency for the class 227–282.5?

Accepted Answer

21

Question 5

Which of the following best describes a relative frequency histogram?

Accepted Answer

A bar graph where the height of each bar represents the percentage of data values in each class.

Question 6

Given a class with lower class boundary 115 and upper class boundary 170.5, what is the midpoint of this class?

Accepted Answer

$$\frac{115 + 170.5}{2} = 142.75$$

Question 7

If the sum of all relative frequencies in a frequency distribution is calculated, what should the result be?

Accepted Answer

$$1$$

Question 8

A stem-and-leaf plot is constructed for the following grades: 53, 56, 61, 68, 70, 72, 75, 80, 83, 83, 87, 89, 89, 92, 94, 94, 97, 99, 100. What is the stem for the grade 83?

Accepted Answer

8

Question 9

Which of the following statements about a Pareto chart is correct?

Accepted Answer

It displays categories in descending order of frequency.

Question 10

In a scatter plot of age and internet usage, the points show a downward trend. What type of correlation does this indicate?

Accepted Answer

Negative correlation

Question 11

If a pie chart is constructed from the following data: Comedy (4), Romance (6), Action (5), Drama (1), SciFi (4), what is the relative frequency for Action?

Accepted Answer

$$\frac{5}{20} = 0.25$$

Question 12

Which of the following best describes the cumulative frequency for a class interval?

Accepted Answer

The sum of the frequencies for that class and all previous classes.

Question 13

What is the formula for the relative frequency of a class if $$f is $$the class frequency and $$n is $$the sample size?

Accepted Answer

$$\frac{f}{n}$$

Question 14

A frequency polygon is constructed using which of the following on the x-axis?

Accepted Answer

Class midpoints

Question 15

If the range of a data set is 391 and you want to create 7 classes, what is the class width? (Round up to the next whole number.)

Accepted Answer

$$\frac{391}{7} = 56$$

Question 16

Which of the following is NOT a reason to use a frequency class table?

Accepted Answer

To display the relationship between two variables

Question 17

In constructing a frequency distribution, what is the formula for the class boundaries?

Accepted Answer

Lower class boundary = lower class limit - half distance; Upper class boundary = upper class limit + half distance

Question 18

A cumulative frequency graph (ogive) is used to:

Accepted Answer

Show the running total of frequencies up to each class boundary

Question 19

If a class has a lower class limit of 200 and an upper class limit of 249, what is the class width?

Accepted Answer

$$249 - 200 + 1 = 50$$

Question 20

Which of the following is a key difference between a histogram and a bar graph?

Accepted Answer

A histogram is used for quantitative data and bars touch; a bar graph is used for qualitative data and bars do not touch.

Frequency Distributions and Graphs in Statistics: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard