Question 1

Which level of measurement is most appropriate for recording the temperatures of the ocean at various depths?

Accepted Answer

Interval

Question 2

An author mailed 120,000 questionnaires and received 7,431 responses. What is the main reason her conclusions may not be valid for the general population?

Accepted Answer

No, it was a voluntary response sample.

Question 3

Given the frequency distribution of age groups, which of the following best describes the lower class limits?

Accepted Answer

The smallest value in each class interval.

Question 4

A frequency table is constructed for the ages of award-winning actors. What is the main purpose of using class intervals such as 20-29, 30-39, etc.?

Accepted Answer

To organize the data into meaningful groups.

Question 5

A study was conducted to determine time spent on job tasks. Which type of graph would be most effective for comparing the frequencies of different job categories?

Accepted Answer

Bar chart

Question 6

When comparing two soda brands, the volumes of soda in each can are measured. Which statistical measure would best summarize the central tendency of the volumes?

Accepted Answer

Mean

Question 7

Given a data set of amounts of salt in containers, which measure is most affected by extreme values?

Accepted Answer

Mean

Question 8

If the mean height of a group is 67 inches with a standard deviation of 3 inches, what is the z-score for a person with a height of 73 inches?

Accepted Answer

$$z = \frac{73 - 67}{3} = 2$$

Question 9

Two orders are randomly selected from a fast food restaurant. What is the probability that both orders are accurate if the probability of one accurate order is $$0.75$$?

Accepted Answer

$$0.75 	imes 0.75 = 0.5625$$

Question 10

A drug testing company finds 10 positive results among 100 subjects. If one subject is randomly selected, what is the probability that the subject tested negative?

Accepted Answer

$$\frac{90}{100} = 0.9$$

Question 11

If a student's alarm clock has a 4.2% failure rate, what is the probability that it works on the morning of an important exam?

Accepted Answer

$$1 - 0.042 = 0.958$$

Question 12

When selecting a random sample, why is the probability for a single pick more important than for a sample of picks?

Accepted Answer

The single pick probability is more important because it determines the likelihood for each individual.

Question 13

A bus operator wants to estimate the percentage of passengers who prefer aisle seats. If 15% of passengers prefer aisle seats, what is the sample percentage?

Accepted Answer

$$15\%$$

Question 14

A brand manager surveys adults at a college to estimate the percentage who have heard of a brand. Why might this sample not represent all adults?

Accepted Answer

The sample is not random and may not represent the population.

Question 15

A drug is used to treat blood clot pain. Among 610 patients treated with the drug, 90 reported adverse reactions. What is the best point estimate of the population proportion?

Accepted Answer

$$\frac{90}{610} \approx 0.148$$

Question 16

In a clinical trial, cholesterol levels are measured before and after treatment. What is the confidence interval formula for the population mean?

Accepted Answer

$$\bar{x} \pm z \frac{\sigma}{\sqrt{n}}$$

Question 17

A hypothesis test results in a p-value of 0.045. If the significance level is $$\alpha = 0.05$$, what is the correct conclusion?

Accepted Answer

Reject the null hypothesis because the p-value is less than $$\alpha.$$

Question 18

The best predicted value of y for an actual value where x = 10 is given by $$y = 2.5x + 3. $$What is the predicted value?

Accepted Answer

$$y = 2.5 	imes 10 + 3 = 28$$

Question 19

If the linear correlation coefficient $$r = 0.82$$, what does this indicate about the relationship between two variables?

Accepted Answer

There is a strong positive linear relationship.

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