Question 1

Which of the following best describes inferential statistics?

Accepted Answer

Using sample data to make estimates, decisions, predictions, or other generalizations about a population of interest.

Question 2

A manager records the wait times of 200 customers at a franchise location to estimate the average wait time for all customers. In this scenario, what is the population of interest?

Accepted Answer

All customers at the franchise location.

Question 3

Which of the following is an example of qualitative data?

Accepted Answer

Favorite color of students.

Question 4

A researcher wants to study the effect of a new training program on employee productivity. She randomly assigns employees to either the new program or the standard program and measures their output. What type of data collection method is this?

Accepted Answer

Experiment.

Question 5

If a survey about illegal drug use at a university results in many students refusing to answer due to fear of repercussions, what type of bias has occurred?

Accepted Answer

Nonresponse bias.

Question 6

Given the following frequencies for grades on a test: A: 4, B: 5, C: 7, D: 3, F: 1. What is the relative frequency of students who scored a C?

Accepted Answer

$$0.35$$

Question 7

Which graph type is most appropriate for displaying the distribution of monthly sales figures for a business?

Accepted Answer

Histogram.

Question 8

A sample of five students spent the following amounts on food in September: $$300, 200$$, $$250, 400$$, $225. What is the sample mean?

Accepted Answer

$$275$$

Question 9

For the same data set: $$300, 200$$, $$250, 400$$, $225, what is the sample median?

Accepted Answer

$$250$$

Question 10

What is the formula for sample variance $$s^2$$ for a sample of size $$n$$?

Accepted Answer

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

Question 11

A data set has a mean of $$20$$ and a standard deviation of $$4. $$Using Chebyshev's Rule, at least what percentage of data falls within $$12$$ and $$28$$?

Accepted Answer

$$75\%$$

Question 12

If a distribution is mound-shaped and symmetric, approximately what percentage of data falls within two standard deviations of the mean according to the Empirical Rule?

Accepted Answer

$$95\%$$

Question 13

A student scores at the $$87th $$percentile in math and the $$45th $$percentile in reading on the ACT. What does this mean?

Accepted Answer

The student scored higher than $$87\% of $$students in math and higher than $$45\% of $$students in reading.

Question 14

What is the formula for the z-score of a value $$x in a $$data set with mean $$\bar{x}$$ and standard deviation $$s$$?

Accepted Answer

$$z = \frac{x - \bar{x}}{s}$$

Question 15

A police officer finds the mean speed of cars is $$22$$ mph with a standard deviation of $$4$$ mph. If a car drives by at $$33$$ mph, what is the z-score for this speed?

Accepted Answer

$$z = \frac{33 - 22}{4} = 2.75$$

Question 16

According to the z-score method, which observation would be considered an outlier?

Accepted Answer

An observation with a z-score greater than $$3 or $$less than $$-3.$$

Question 17

A sample of car speeds has a mean of $$33$$ mph and a standard deviation of $$5$$ mph. Which of the following speeds would be classified as an outlier?

Accepted Answer

$$50$$ mph

Question 18

Which measure of central tendency is most affected by outliers?

Accepted Answer

Mean.

Question 19

If a data set is right-skewed, which of the following is true?

Accepted Answer

The mean is greater than the median.

Question 20

A business analyst wants to compare the variability of monthly sales between two stores. Which statistic should she use?

Accepted Answer

Standard deviation.

Statistics for Business: Exam 1 Review Study Notes

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