Exam 5: Discrete Random Variables

A manufacturer tested a sample of semiconductor chips and found that 35 were defective and 190 were good.If additional tests are to be conducted with random samples of 160 semiconductor chips,find the mean for the number of defects in these groups of 160 (rounded to nearest whole number).

If n = 15 and p = .4,then the standard deviation of the binomial distribution is

The J.O.Supplies Company buys calculators from a Korean supplier.The probability of a defective calculator is 10%. If 100 calculators are selected at random,what is the standard deviation of the number of defectives?

A lawyer believes that the probability is .3 that she can win a discrimination suit.If she wins the case she will make $40,000,but if she loses she gets nothing.Assume that she has to spend $5000 preparing the case.What is her expected gain?

If x is a Poisson random variable with a mean of 10,what is the probability that x is greater than or equal to 2?

A large disaster cleaning company estimates that 30% of the jobs it bids on are finished within the bid time.Looking at a random sample of 8 jobs that is has contracted: Calculate the probability that exactly 4 of the jobs were not completed within the bid time.

In the most recent election,19% of all eligible college students voted.If a random sample of 20 students were surveyed: Find the probability that none of the students voted.

An important part of the customer service responsibilities of a cable company relates to the speed with which trouble in service can be repaired.Historically,the data show that the likelihood is 0.75 that troubles in a residential service can be repaired on the same day.For the first five troubles reported on a given day,what is the probability that: Fewer than two troubles will be repaired on the same day?

A company manufactures an appliance,gives a warranty and 95% of its appliances do not require repair before the warranty expires.If an organization buys 10 of these appliances,calculate an interval that contains 95.44% of all the appliances that won't require repair.

The number of calls coming into a PBX follows a Poisson process with a mean of 120 calls per hour.What is the probability of no calls in a one-minute interval?

The number of ways to arrange x successes among n trials is equal to

An insurance company will insure a $75,000 Hummer for its full value against theft at a premium of $1500 per year.Suppose that the probability that the Hummer will be stolen is 0.0075. Find the premium that the insurance company should charge if its wants it's expected net profit to be $2000?

Which of the following statements about the binomial distribution is not correct?

Consider the experiment of tossing a fair coin three times and observing the number of heads that result (X = number of heads). What is the standard deviation for this distribution?

An important part of the customer service responsibilities of a cable company relates to the speed with which trouble in service can be repaired.Historically,the data show that the likelihood is 0.75 that troubles in a residential service can be repaired on the same day.For the first five troubles reported on a given day,what is the probability that: At least 3 troubles will be repaired on the same day.

An important part of the customer service responsibilities of a cable company relates to the speed with which trouble in service can be repaired.Historically,the data show that the likelihood is 0.75 that troubles in a residential service can be repaired on the same day.For the first five troubles reported on a given day,what is the probability that: All five will be repaired on the same day?

Consider a Poisson distribution with an average of 3 customers per minute at the local grocery store.Determine the expected number of customer arrivals for a five-minute period

A total of 50 raffle tickets are sold for a contest to win a car.If you purchase one ticket,what are your odds against winning?

The requirement that the probability of success remains constant from trial to trial is a property of the _________________ distribution.

Consider the experiment of tossing a fair coin three times and observing the number of heads that result (X = number of heads). What is the variance for this distribution?