Question 1

A researcher wants to estimate the average number of hours college students sleep each night. A random sample of 60 students is selected. Which statistical procedure is most appropriate?

Accepted Answer

One-sample t interval for $$\mu$$

Question 2

A company wants to know whether fewer than 35% of its customers purchase an extended warranty. A random sample of 450 customers is selected. Which statistical procedure should be used?

Accepted Answer

One-sample z test for $$p$$

Question 3

Researchers want to determine whether gender is related to preferred social media platform. Which statistical test is most appropriate?

Accepted Answer

Chi-square test of independence

Question 4

Researchers compare the average GPA of online students and traditional classroom students. Different students are in each group. Which statistical test should be used?

Accepted Answer

Two-sample t test

Question 5

A school randomly selects 25 students from each grade level to participate in a survey. What sampling method is this?

Accepted Answer

Stratified sampling

Question 6

Which boxplot has the largest interquartile range (IQR)?

Accepted Answer

The one with the widest box

Question 7

A survey of 800 voters finds that 496 support a tax increase. The value $$\frac{496}{800} is $$called:

Accepted Answer

Statistic

Question 8

In a survey where 800 voters are polled and 496 support a tax increase, what is the sample?

Accepted Answer

The 800 surveyed voters

Question 9

Researchers randomly assign patients to receive either Drug A or Drug B and compare outcomes. This is an example of:

Accepted Answer

Experimental study

Question 10

A teacher randomly selects one classroom and surveys every student in that classroom. Which sampling method is used?

Accepted Answer

Cluster sampling

Question 11

A histogram has a long tail extending toward smaller values. The distribution is:

Accepted Answer

Left skewed

Question 12

Which of the following are ALL categorical variables?

Accepted Answer

Favorite pizza topping, ZIP code, Hair color

Question 13

Which of the following are ALL quantitative variables?

Accepted Answer

Number of siblings, Height, Income

Question 14

A medical test fails to detect a disease in someone who actually has it. This is an example of:

Accepted Answer

Type II error

Question 15

According to the Central Limit Theorem, which of the following is true?

Accepted Answer

The sampling distribution of $$\bar{x}$$ becomes approximately normal for sufficiently large samples.

Question 16

Two 95% confidence intervals are constructed using sample sizes of 40 and 200. Why is the interval based on $$n=200$$ narrower?

Accepted Answer

Larger sample size reduces standard error

Question 17

A chi-square test reports $$\$$chi^2$$ = 9.12$$, $$p = 0.018$$, $$\alpha = 0.05. $$What conclusion should be made?

Accepted Answer

Reject $$H_0. $$There is evidence of an association.

Question 18

A standard deck of 52 cards is shuffled. What is the probability of drawing an Ace? Round to four decimals.

Accepted Answer

$$0.0769$$

Question 19

The weights of apples are normally distributed with $$\mu = 180$$ grams and $$\sigma = 20$$ grams. A sample of $$n = 64$$ apples is selected. What is $$P(\bar{x} \u003c 176)$$?

Accepted Answer

$$P(\bar{x} \u003c 176) = 0.0228$$

Question 20

Given the regression equation $$\hat{y} = 58 + 4.2x$$, what is the interpretation of the slope?

Accepted Answer

For each increase of 1 in $$x$$, $$y$$ increases by 4.2 units.

Question 21

A random sample of 36 engines has $$\bar{x} = 1250$$ hours and $$s = 90$$ hours. Construct a 95% confidence interval for the population mean. Which formula should be used?

Accepted Answer

$$\bar{x} \pm t^* \frac{s}{\sqrt{n}}$$

STA 215 Final Exam Practice #2 – Step-by-Step Statistics Guidance

Guida di studio - Domande di pratica

Study guide - Flashcard