Exam 6: Discrete Probability Distributions

A project has 3 independent stages that must be completed in sequence.The time to complete each stage is a random variable.The standard deviations of the completion times for the stages are σ₁ = 5,σ₂ = 4,σ₃ = 6.The standard deviation of the overall project completion time is:

The CDF for the geometric distribution shows:

The expected value of a random variable X is 10 and the standard deviation is 2.The standard deviation of the random variable Y = 2X - 10 is:

To ensure quality,customer calls for airline fare quotations are monitored at random.On a particular Thursday afternoon,ticket agent Bob gives 40 fare quotations,of which 4 are incorrect.In a random sample of 8 of these customer calls,which model best describes the number of incorrect quotations Bob will make?

A die is rolled.If it rolls to a 1,2,or 3 you win $2.If it rolls to a 4,5,or 6 you lose $1.Find the expected winnings.

A random variable is binomially distributed with n = 16 and π = .40.The expected value and standard deviation of the variables are:

Ten percent of the corporate managers at Axolotl Industries majored in humanities.What is the expected number of managers to be interviewed until finding the first one with a humanities major?

Which statement concerning the binomial distribution is correct?

There is a .02 probability that a customer's Visa charge will be rejected at a certain Target store because the transaction exceeds the customer's credit limit.What is the expected number of Visa transactions until the first one is rejected?

If X is a discrete uniform random variable ranging from one to eight,its mean is:

If tubing averages 16 defects per 100 meters,what is the probability of finding exactly 2 defects in a randomly chosen 10-meter piece of tubing?

When π = .70 the discrete binomial distribution is negatively skewed.

The expected value of a random variable is its mean.

There is a .02 probability that a customer's Visa charge will be rejected at a certain Target store because the transaction exceeds the customer's credit limit.What is the probability that the first such rejection occurs on the third Visa transaction?

On average,a major earthquake (Richter scale 6.0 or above)occurs three times a decade in a certain California county.Find the probability that at least one major earthquake will occur within the next decade.

The hypergeometric distribution is not applicable if sampling is done with replacement.

Which distribution is most nearly appropriate to describe the number of fatalities in Texas in a given year due to poisonous snakebites?

The geometric distribution best describes:

A discrete probability distribution:

If the probability of success is .30,what is the probability of obtaining the first success within the first five trials?