hcc business stats.

If you are counting the number of customers visiting your store on a given day, you are working with continuous data.

False

Rating the satisfaction of a hotel room on a 1-5 scale is an example of a discrete random variable.

True

Discrete random variables have outcomes that typically take on whole numbers as a result of conducting an experiment.

true

Discrete random variables have outcomes that take on any numerical value as a result of conducting an experiment.

false

The ounces of soda consumed by an adult next month are an example of a discrete random variable.

false

A listing of all the possible outcomes of an experiment for a discrete random variable along with the relative frequency of each outcome is called a discrete probability distribution.

true

In a discrete probability distribution, the value of the random variable can fall into more than one of the frequency distribution classes.

false

Which of the following is not a condition of a discrete probability distribution?

the probability of success must exceed the probability of failure

The mean of a discrete probability distribution is the weighted average of the outcomes of the random variables that comprise it.

true

The mean of a discrete probability distribution needs to equal one of the values of the random variables.

false

An expected value is another term for the mean of a probability distribution.

true

The mean and standard deviation for discrete probability distributions are useful when comparing two different distributions.

true

Because of the ambiguity of the intervals, technically, it's not proper to calculate the mean and standard deviation of ordinal data.

true

The expected value of sample information is the mean of a discrete probability distribution when the discrete random variable is expressed in terms of dollars.

false

The ________ of a discrete probability distribution measures the dispersion of each outcome of the random variable from the mean of the distribution.

standard deviation

A novel on the Amazon.com web site has the following ratings, in number of stars, from reviewers:

1.25

The table below shows the numbers of two- to five-bedroom houses in the Belmont neighborhood.

3.82

The following table shows the number of pieces of junk mail that arrives in my mailbox each day.

4.44

What is the standard deviation for the number of pieces of junk mail received per day?

1.24

"No shows" are the people with reservations who fail to arrive. The following table shows the number of no shows each day at a hotel over the last 125 business days.

.232

When the discrete random variable is expressed in terms of dollars, the mean of the distribution is known as the ________________________.

expected monetary value

Testing whether a part is defective or not defective after it has been manufactured would be best described using a binomial probability distribution.

true

Observing whether a customer purchases or does not purchase an extended warranty for a new laptop would be best described using a uniform probability distribution.

false

An exponential probability distribution allows us to calculate the probability of a specific number of successes for a certain number of trials.

false

The equation used to calculate binomial probabilities relies on permutations of n objects selected x at a time.

false

The number of successes in a binomial experiment must range from zero to n.

true

In a binomial experiment, the number of successes can never exceed the number of trials.

true

The mean of the binomial distribution represents the long-term average number of successes to expect based on the number of trials conducted.

true

The probability of a binomial distribution represents the variation that we would see in the number of successes over n trials, assuming the chance of a success is p.

false

Which of the following is not a characteristic of a binomial experiment?

the probability of a success must exceed the probability of a failure

According to LIMRA, 77% of husband-wife families with kids under 18 years old have life insurance. A random sample of six husband-wife families was selected. What is the probability that less than two families have life insurance?

.0029

According to the Insurance Research Council, 14% of U.S. drivers are uninsured. A random sample of seven drivers was selected. What is the probability that less than two of these drivers are uninsured?

.7444

According to the Mortgage Bankers Association, 11% of U.S. mortgages were delinquent last year. A delinquent mortgage is one that has missed at least one payment but has not yet gone to foreclosure. A random sample of eight mortgages was selected. What is the probability that less than three of these mortgages are delinquent?

.9794

According to the Insurance Research Council, 14% of U.S. drivers are uninsured. A random sample of seven drivers was selected. What is the standard deviation of this distribution?

.918

According to the Centers for Medicare & Medicaid Services, 21% of nursing homes in the United States received five stars in overall ratings on a scale of 1 to 5. A random sample of seven nursing homes was selected. What is the probability that more than one of them received five stars?

.4506

The number of typographical errors found in a manuscript would best be described using a Poisson probability distribution.

true

The number of occurrences in a Poisson distribution must range from zero to n.

false

The Poisson distribution can be used to approximate the binomial distribution when the number of trials is greater than 20 and the probability of success is less than or equal to 0.05.

true

A ________ distribution is useful for calculating the probability that a certain number of events will occur over a specific interval of time or space

Poisson

The mean and the variance are equal for a ________ probability distribution.

Poisson

A company that bakes chocolate chip cookies averages 5.2 chocolate chips per cookie. Assume that the number of chocolate chips per cookie follows the Poisson distribution. What is the probability that a randomly selected cookie will contain one or two chocolate chips?

.1033

Assume that the number of customers who arrive at a water ice stand follows the Poisson distribution with an average rate of 6.4 per 30 minutes. What is the probability that exactly five customers will arrive during the next 30 minutes?

.1487

Dwight Howard plays center in the National Basketball Association and averaged 1.8 blocked shots per game during a recent season. Assume that the number of blocked shots per game follows the Poisson distribution. What is the probability that Dwight Howard will block exactly one shots during the next game?

.2974

According to the Deloitte EV Survey, 5% of respondents indicated that they would be willing to pay an extra $500 or more for an electric vehicle versus one with a gasoline engine. A random sample of 25 adults has been selected. Use the Poisson distribution to approximate the binomial distribution to determine the probability that more than two adults from this sample would be willing to pay an extra $500 or more for an electric vehicle versus one with a gasoline engine.

.1316

Continuous random variables are outcomes that take on any numerical value in an interval as a result of conducting an experiment

true

The probability that a continuous random variable equals a specific value is always equal to 1.0.

false

Continuous random variables can take on values between whole integers that contain decimal points.

true

The time between customer arrivals is a common application for the uniform probability distribution.

false

Which of the following probability distribution is not continuous?

poisson

Which of the following experiments does not generate a continuous random variable?

counting the number of customers who enter a store during the business day

For continuous distributions, the probability that x is less than or equal to a value is the same as the probability that x is less than that value

true

The area under the curve of the normal probability distribution is always equal to 1.0.

true

the left and right ends of the normal probability distribution extend indefinitely, never quite touching the horizontal axis.

true

A normal probability distribution's standard deviation (σ) completely describes its shape.

false

The mathematical expression that describes the shape of normal curves is known as the normal probability density function

true

The z-score in a normal probability distribution determines the number of standard deviations that a particular value, x, is from the mean.

true

The z-score follows a normal distribution with μ = 1 and σ = 0, which is known as the standard normal distribution

false

Any normally distributed values can be standardized with z-scores

true

According to the Central Limit Theorem, if a distribution follows a bell-shaped, symmetrical curve centered around the mean, approximately 68, 95, and 99.7 percent of its values will fall within one, two, and three standard deviations above and below the mean respectively.

false

The continuity correction factor allows us to approximate the binomial distribution with the exponential distribution by adding and subtracting the value 0.5 to create the interval of interest.

false

The ________ probability distribution is useful when the majority of the data tend to be in the middle of the distribution.

normal

Which of the following statements is true regarding the normal probability distribution?

the mean and median are roughly equal to one another

A smaller standard deviation for the normal probability distribution results in

a skinnier curve that is tighter and taller around the mean

Which of the following statements is true regarding z-scores for the normal probability distribution?

z-scores are negative for values of x that are less than the distribution mean.

The time for a professor to grade an exam is normally distributed with a mean of 16.3 minutes and a standard deviation of 4.2 minutes. What is the probability that a randomly selected exam will require less than 20 minutes to grade?

.9230

The time for a professor to grade an exam is normally distributed with a mean of 16.3 minutes and a standard deviation of 4.2 minutes. The interval around the mean that contains 68% of the times needed to grade exams is ________.

12.1, 20.5

The ________ probability distribution is used to describe data where lower values tend to dominate and higher values don't occur very often.

exponential

A discrete random variable that follows the Poisson distribution with a mean equal to λ has a counterpart continuous random variable that follows the ________ distribution with a mean equal to μ = 1/λ.

exponential

The shape of the exponential distribution is ________.

right-skewed

DLP projectors are used in the majority of cinema projection systems and require a special light bulb to display a picture. Assume that the average life of a DLP bulb is 2,000 hours and that this failure time follows the exponential distribution. What is the probability that a randomly selected bulb will last more than 2,500 hours?

.2865

DLP projectors are used in the majority of cinema projection systems and require a special light bulb to display a picture. Assume that the average life of a DLP bulb is 2,000 hours and that this failure time follows the exponential distribution. What is the probability that a randomly selected bulb will last between 1,500 and 2,200 hours?

.1395

Assume that the average talk time on an Apple iPhone is 20 hours and that this time follows the exponential probability distribution. What is the probability that a randomly selected iPhone will experience less than 15 hours of talk time?

.5276

Suppose the average tread-life of a certain brand of tire is 42,000 miles and that this mileage follows the exponential probability distribution. What is the probability that a randomly selected tire will have a tread-life between 30,000 and 50,000 miles?

.1854