Question 1

Given the data set: 10, 19, 25, 26, 28, 30, 38, 41, 43, 43, 46, 60, 64, 71, 80, 100, 100, 100, is this data considered quantitative or qualitative?

Accepted Answer

Quantitative, because the values are numerical.

Question 2

For the data set above, which measure of central tendency would be most affected by extreme values (outliers)?

Accepted Answer

Mean

Question 3

What is the formula for the sample standard deviation $s$ of a data set $x_1, x_2, ..., x_n$?

Accepted Answer

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

Question 4

If a distribution is symmetric and bell-shaped, which measure of central tendency is most appropriate to describe its center?

Accepted Answer

Mean

Question 5

A study finds the heights of gorillas are normally distributed with mean $\mu = 175$ cm and standard deviation $\sigma = 8$ cm. What proportion of gorillas would you expect to have heights between 159 cm and 191 cm?

Accepted Answer

About 95%

Question 6

A qualitative variable with three classes (A, B, C) is measured for each of 10 subjects. The data observed is: A, C, C, B, A, C, B, A, B, C. What is the frequency for class B?

Accepted Answer

3

Question 7

In a histogram, the class width is defined as:

Accepted Answer

The difference between the upper and lower boundaries of a class.

Question 8

A histogram of RDER values for 75 subjects is shown. If the histogram is skewed right, what does this indicate about the data?

Accepted Answer

Most values are concentrated on the lower end.

Question 9

Maria scored 98 on a test with a mean of 80 and a standard deviation of 5. What is her $z$-score?

Accepted Answer

$z = \frac{98 - 80}{5} = 3.6$

Question 10

Given the following data for antibody concentration (x) and wicking length (y): (0.21, 22.3), (0.41, 19.5), (0.63, 14.3), (1.15, 13.5), (1.25, 12.5), what is the formula for the least-squares regression line?

Accepted Answer

$y = b_0 + b_1 x$

Question 11

What does the correlation coefficient $r$ measure?

Accepted Answer

The strength and direction of a linear relationship between two variables.

Question 12

If the correlation coefficient $r$ is close to 0, what does this indicate?

Accepted Answer

There is little to no linear relationship.

Question 13

Which of the following is NOT a measure of spread?

Accepted Answer

Median

Question 14

If a data set has a mean of 50 and a standard deviation of 10, what is the value that is two standard deviations above the mean?

Accepted Answer

70

Question 15

Which of the following best describes the median?

Accepted Answer

The value that divides the data set into two equal halves.

Question 16

In a frequency distribution, what does the relative frequency represent?

Accepted Answer

The proportion of the total number of observations in a class.

Question 17

If the mean is greater than the median in a data set, the distribution is most likely:

Accepted Answer

Skewed right

Question 18

Which of the following is a real-world example of a qualitative variable?

Accepted Answer

Blood type (A, B, AB, O)

Question 19

If a scatterplot shows points closely clustered around a straight line that slopes downward, what can you conclude about the correlation?

Accepted Answer

There is a strong negative correlation.

Question 20

Which of the following is the correct interpretation of the slope $b_1$ in a regression equation $y = b_0 + b_1 x$?

Accepted Answer

The change in $y$ for a one-unit increase in $x$.

Exam 1 Review: Descriptive Statistics, Distributions, and Correlation

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