Question 1

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

Accepted Answer

Interval

Question 2

A researcher mails 120,000 questionnaires and receives 7,431 responses. What is the main concern with using these responses to generalize to the entire population?

Accepted Answer

No, it was a voluntary response sample.

Question 3

Given the following age group frequency distribution, what are the lower class limits?

Age (years): 10-14, 15-19, 20-24, 25-29, 30-34, 35-39
Frequency: 2, 5, 7, 6, 4, 3

Accepted Answer

$$10, 15, 20, 25, 30, 35$$

Question 4

A frequency table is constructed for the ages of award-winning male actors using class intervals of 20-29, 30-39, 40-49, 50-59, 60-69, 70-79. If the data are: 38, 42, 50, 34, 60, 41, 37, 47, 56, 70, 33, 39, 44, 51, 48, 36, 53, 45, 62, 57, 40, 35, 49, 55, 43, 46, 52, 54, 58, 63, 59, 61, 65, 66, 68, 69, 71, 73, 75, 77, how many actors are in the 40-49 age group?

Accepted Answer

9

Question 5

A study is conducted to determine how people get gifts. The data show: Internet search (45), Executive search firm (30), Networking (60), Data mining (15). If someone wants to get a gift, which method is most effective based on the highest frequency?

Accepted Answer

Networking

Question 6

Given the following volumes of soda (in mL): 500, 502, 498, 501, 499, 500, 503, 497, 504, 496, does the configuration of the points appear to suggest that the volumes are from a population with a normal distribution?

Accepted Answer

Yes, the population does have a normal distribution because the frequencies of the volume classes form a bell shape.

Question 7

Given the data set: 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, find the median.

Accepted Answer

$$210$$

Question 8

A student has a test score of 85 with a mean of 80 and a standard deviation of 5. What is the z-score for the student's test score?

$$z = \frac{X - \mu}{\sigma}$$

Accepted Answer

$$z = 1$$

Question 9

A table shows drive-thru order accuracy at four fast food chains. If two orders are selected at random with replacement, what is the probability that both are accurate if the probability of an accurate order is $$0.85$$?

Accepted Answer

$$0.7225$$

Question 10

A drug test is conducted among 1,000 subjects. There are 10 true positives, 5 false positives, 985 true negatives, and 0 false negatives. What is the probability that a randomly selected subject tested negative and did not use marijuana?

Accepted Answer

$$0.985$$

Question 11

A student's alarm clock has a 4.2% failure rate. What is the probability that the alarm clock will work on two consecutive mornings?

Accepted Answer

$$0.958^2$$

Question 12

Assume that adult male IQ scores are normally distributed with a mean of $$100$$ and a standard deviation of $$15. $$What is the probability that a randomly selected adult male has an IQ greater than $$120$$?

Accepted Answer

$$0.0918$$

Question 13

When comparing the probability of a single pilot's performance to the probability for a sample of pilots, which is more relevant for airline safety?

Accepted Answer

The probability for a sample of pilots is more relevant because it reflects the average performance of the group.

Question 14

A bus operations manager wants to estimate the percentage of passengers who prefer aisle seats. If a random sample of 100 passengers yields a sample percentage of 35%, what is the 95% confidence interval for the population proportion?

$$\hat{p} \pm z^* \sqrt{\frac{\hat{p}(1-\hat{p})}{n}}$$

Accepted Answer

$$0.35 \pm 0.096$$

Question 15

A brand manager surveys 200 adults at a college and finds that 80% have heard of the brand. Why might this sample not be representative of all adults?

Accepted Answer

A sample of students at a college is a convenience sample, so it is very possible that the results would not be representative of the population of adults.

Question 16

A clinical trial tests a new drug to lower blood cholesterol. Among 470 patients, 410 improved. Construct a 90% confidence interval for the proportion of patients who improved.

$$\hat{p} \pm z^* \sqrt{\frac{\hat{p}(1-\hat{p})}{n}}$$

Accepted Answer

$$0.872 \pm 0.027$$

Question 17

A study tests the effectiveness of garlic in lowering cholesterol. The mean change in LDL cholesterol is measured before and after treatment. What does it mean if the 95% confidence interval for the mean difference does not contain zero?

Accepted Answer

There is significant evidence that garlic has an effect on LDL cholesterol levels.

Question 18

A hypothesis test is conducted at $$\alpha = 0.01$$ and the p-value is $$0.045. $$What is the correct conclusion?

Accepted Answer

Fail to reject $$H_0$$ because the p-value is greater than $$\alpha.$$

Question 19

The least squares regression line for predicting adult male weight (kg) from height (cm) is $$\hat{y} = -100 + 1.1x. $$What is the predicted weight for a man who is 180 cm tall?

Accepted Answer

$$98 kg$$

Question 20

A correlation coefficient $$r = 0.85 is $$calculated between the number of hours studied and exam scores. What does this indicate?

Accepted Answer

There is a strong positive linear relationship between hours studied and exam scores.

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