Q: Which of the following is the correct formula for the relative frequency of a category?

$\text{relative frequency} = \frac{\text{frequency}}{\text{sum of all frequencies}}$

Question 1

Which of the following best describes a parameter in statistics?

Accepted Answer

A value that summarizes a characteristic of a population.

Question 2

A researcher wants to study the effect of a new drug on blood pressure. She randomly assigns 100 patients to receive either the drug or a placebo and measures their blood pressure after 6 weeks. What type of study is this?

Accepted Answer

Designed experiment

Question 3

Which sampling method involves dividing the population into groups and then randomly selecting some groups to include all their members in the sample?

Accepted Answer

Cluster sampling

Question 4

A frequency distribution for qualitative data lists:

Accepted Answer

Each category of data and the number of occurrences for each category.

Question 5

Which of the following is the correct formula for the sample mean $\bar{x}$ of $n$ observations $x_1, x_2, ..., x_n$?

Accepted Answer

$\bar{x} = \frac{\sum_{i=1}^n x_i}{n}$

Question 6

A data set has a mean of 50 and a standard deviation of 5. What is the z-score for a value of 60?

Accepted Answer

$z = \frac{60 - 50}{5} = 2$

Question 7

Which of the following is NOT a valid method of random sampling?

Accepted Answer

Convenience sampling

Question 8

If a distribution is skewed right, which of the following is true?

Accepted Answer

The mean is greater than the median.

Question 9

A boxplot is constructed using which of the following five-number summary values?

Accepted Answer

Minimum, Q1, median, Q3, maximum

Question 10

Which formula is used to calculate the sample standard deviation $s$ for $n$ observations $x_1, x_2, ..., x_n$ with sample mean $\bar{x}$?

Accepted Answer

$s = \sqrt{\frac{\sum_{i=1}^n (x_i - \bar{x})^2}{n-1}}$

Question 11

A researcher surveys every 10th person entering a hospital. What type of sampling method is being used?

Accepted Answer

Systematic sampling

Question 12

Which of the following is an example of a discrete quantitative variable?

Accepted Answer

The number of cars in a parking lot

Question 13

Which of the following best describes the purpose of blocking in experimental design?

Accepted Answer

To group similar experimental units together to control for confounding variables

Question 14

If a histogram of a data set is bell-shaped and symmetric, which measure of central tendency is most appropriate to use?

Accepted Answer

Mean

Question 15

A study finds that 80% of a sample of 2000 adults favor a new public policy. What is the correct term for the value 80% in this context?

Accepted Answer

Statistic

Question 16

Which of the following is the correct formula for the interquartile range (IQR)?

Accepted Answer

$IQR = Q_3 - Q_1$

Question 17

According to the Empirical Rule, approximately what percentage of data falls within two standard deviations of the mean in a bell-shaped distribution?

Accepted Answer

95%

Question 18

Which of the following is a potential source of bias in survey sampling?

Accepted Answer

Nonresponse from selected individuals

Question 19

A pie chart is most appropriate for displaying which type of data?

Accepted Answer

Qualitative (categorical) data

Question 20

Which of the following is the correct formula for the relative frequency of a category?

Accepted Answer

$	ext{relative frequency} = \frac{	ext{frequency}}{	ext{sum of all frequencies}}$

Foundations of Statistics: Data Collection, Organization, and Summarization

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