Exam 5: Discrete Random Variables

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

A pharmaceutical company has determined that if a new cholesterol-reducing drug is manufactured (introduced to the market),the following probability distribution will describe the contribution of this drug to their profits during the next six months. The company management has decided to market this product if the expected contribution to profit for the next six months is more than $90,000.Based on the information given above,should the company begin manufacturing the new drug? Explain your answer.

For a binomial process,the probability of success is 40 percent and the number of trials is 5.Find P(X > 4).

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

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?

The manager of the local grocery store has determined that,on average,4 customers use the service desk every half-hour.Assume that the number of customers using the service desk has a Poisson distribution.What is the probability that during a randomly selected half-hour period,exactly 2 customers use the service desk?

Depending on the mean of the Poisson distribution,the distribution can either be very skewed to the right or quite symmetrical.

In a binomial experiment,the results of one trial are dependent on the results of other trials.

A random variable:

If the probability of a success on a single trial is .2,what is the probability of obtaining 3 successes in 10 trials if the number of successes is binomial?