Question 1

A nutritionist wants to estimate the mean daily sodium intake of adults in a city. A random sample of 800 adults is selected and their sodium intake is recorded. Which statistical procedure is most appropriate?

Accepted Answer

One sample z interval for $$p$$

Question 2

A company wants to estimate the proportion of customers who prefer Brand A over Brand B. A random sample of 1,200 customers is surveyed. Which statistical procedure should be used?

Accepted Answer

One sample z interval for $$p$$

Question 3

A researcher wants to determine whether pet ownership (pet owner or not) is independent of home ownership (owns or rents). A survey of 600 adults is conducted. Which statistical test is most appropriate?

Accepted Answer

Chi-square test for independence

Question 4

Researchers compare the average blood pressure of patients receiving Treatment A and Treatment B. The groups consist of different individuals. Which statistical procedure should be used?

Accepted Answer

Two sample t test for $$\mu$$

Question 5

A researcher divides a population into urban, suburban, and rural residents and randomly selects individuals from each group. Which sampling method is described?

Accepted Answer

Stratified sample

Question 6

A survey asks 2,000 adults whether they exercise at least three times per week. Of the respondents, 1,150 answer “yes.” The value $$\frac{1150}{2000} is an $$example of:

Accepted Answer

A statistic

Question 7

A survey asks 2,000 adults whether they exercise at least three times per week. What does the sample consist of?

Accepted Answer

The 2,000 respondents

Question 8

Researchers randomly assign 300 participants to receive either a new allergy medication or a placebo. Symptoms are recorded after two weeks. What type of study is this?

Accepted Answer

Experimental study because a treatment was administered

Question 9

A teacher writes every student’s name on a slip of paper, places them in a container, and randomly selects five names. What type of sampling is being used?

Accepted Answer

Simple random sample

Question 10

A histogram shows most observations concentrated on the left side with a long tail extending to the right. The distribution is:

Accepted Answer

Skewed to the right

Question 11

A medical screening test incorrectly identifies a healthy patient as having a disease. What type of error has occurred?

Accepted Answer

Type I error

Question 12

According to the Central Limit Theorem, when the sample size is sufficiently large, the sampling distribution of the sample mean will be:

Accepted Answer

Approximately normal regardless of population shape

Question 13

Two 95% confidence intervals are constructed for the same population mean:
$$n = 50$$: (72, 86)
$$n = 250$$: (77, 81)
Why is the second interval narrower?

Accepted Answer

A larger sample size decreases the standard error

Question 14

A clinical trial compares four different treatments. Two hundred participants are randomly assigned to one of the four treatments. What are the experimental units?

Accepted Answer

The 200 participants

Question 15

A fair die is rolled once. What is the probability of obtaining a number greater than 4? Round to two decimals.

Accepted Answer

$$0.50$$

Question 16

A fair die is rolled once. What is the probability of obtaining a number less than or equal to 5? Round to two decimals.

Accepted Answer

$$0.83$$

Question 17

A study examines the relationship between hours studied ($$x) $$and exam score ($$y). $$The regression equation is: $$\hat{y} = 42 + 3.5x. $$What does the slope represent in this context?

Accepted Answer

For each additional hour studied, the exam score increases by 3.5 points.

Question 18

A study examines the relationship between hours studied ($$x) $$and exam score ($$y). $$The regression equation is: $$\hat{y} = 42 + 3.5x. $$What does the intercept represent in this context?

Accepted Answer

The predicted exam score for a student who studies zero hours is 42.

Question 19

A researcher wants to determine whether there is a relationship between college major and preferred learning format (online, hybrid, face-to-face). A chi-square test of independence is conducted. The output reports: $$\$$chi^2$$ = 12.84$$, $$df = 4$$, $$p-$$value = 0.012. Using $$\alpha = 0.05$$, what conclusion should be made?

Accepted Answer

There is evidence of a relationship between major and preferred learning format.

Question 20

A study compares average weekly sales between employees who received sales training ($$n = 30) $$and those who did not ($$n = 28). $$The 95% confidence interval for $$\mu_1$ - \mu_2$ is (2.1, 7.6) and the two-sample t-test p$-value is 0.004. What does this suggest about the effect of sales training?

Accepted Answer

There is strong evidence that sales training increases average weekly sales.

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