Question 1

Which of the following best defines a point estimate in statistics?

Accepted Answer

A value calculated from a sample that is used to estimate a population parameter.

Question 2

A random variable $$X$$ represents the number of cars passing through a toll booth in an hour. Is $$X$$ discrete or continuous?

Accepted Answer

Discrete, because it can only take integer values.

Question 3

Which of the following is NOT a requirement for a probability distribution?

Accepted Answer

Each probability must be greater than 1.

Question 4

What conditions would produce a negative $$z-$$score?

Accepted Answer

When the observed value is less than the mean.

Question 5

Which symbol is used in confidence interval formulas to represent the sample proportion?

Accepted Answer

$$\hat{p}$$

Question 6

A researcher claims that the mean pulse rate of males is less than 70. If a 95% confidence interval for the mean is $$68 \u003c \mu \u003c 72$$, can this interval justify the claim?

Accepted Answer

No, because 70 is within the confidence interval.

Question 7

Which of the following is a correct interpretation of a 99% confidence interval $$4.1 \u003c \mu \u003c 5.6$$?

Accepted Answer

We are 99% confident that the population mean $$\mu is $$between 4.1 and 5.6.

Question 8

Which of the following is a biased estimator?

Accepted Answer

Sample variance $$s^2$$ calculated without dividing by $$n-1.$$

Question 9

If you are asked to find the 85th percentile in a normal distribution, you are being asked to find:

Accepted Answer

The value below which 85% of the data falls.

Question 10

Which group of terms can be used interchangeably in statistics?

Accepted Answer

Mean, expected value, average

Question 11

Which of the following describes the central limit theorem?

Accepted Answer

As sample size increases, the sampling distribution of the sample mean approaches a normal distribution, regardless of the population's distribution.

Question 12

For a binomial distribution with $$n$$ trials and probability $$p of $$success, which formula finds the standard deviation?

Accepted Answer

$$\sqrt{np(1-p)}$$

Question 13

A random variable $$Y$$ represents the time (in minutes) it takes for a chemical reaction to complete. Is $$Y$$ discrete or continuous?

Accepted Answer

Continuous, because time can be measured to any level of precision.

Question 14

Assume a random variable $$z$$ has a standard normal distribution. How would you find the probability that $$z is $$greater than 1.5?

Accepted Answer

Find $$P(z \u003e 1.5) by $$using the standard normal table to get $$P(z  1.5) = 1 - P(z \u003c 1.5).$$

Question 15

Which of the following does NOT describe the standard normal distribution?

Accepted Answer

It has a mean of 1.

Question 16

Which symbols $$z_{\alpha/2}$$ and $$t_{\alpha/2}$$ are used in confidence interval formulas and are called what?

Accepted Answer

Critical values

Question 17

A binomial experiment consists of 10 trials with a probability of success $$p = 0.3. $$What is the mean of the binomial distribution?

Accepted Answer

$$np = 10 	imes 0.3 = 3$$

Question 18

Which of the following is NOT a property of a density curve?

Accepted Answer

The total area under the curve is less than 1.

Question 19

A generator has a probability of 0.95 of operating successfully. What is the probability that at least one out of two generators fails to operate?

Accepted Answer

$$1 - (0.95 	imes 0.95) = 0.0975$$

Question 20

Given a normal distribution with mean $$\mu = 50$$ and standard deviation $$\sigma = 10$$, what is the $$z-$$score for a value $$x = 65$$?

Accepted Answer

$$z = \frac{65 - 50}{10} = 1.5$$

Step-by-Step Guidance for Introductory Statistics Exam Review (Chapters 5–7)

Study Guide - Practice Questions

Study Guide - Flashcards