Exam 2: Probability Concepts and Applications

A ________ is a numerical statement about the likelihood that an event will occur.

The number of cell phone minutes used by high school seniors follows a normal distribution with a mean of 500 and a standard deviation of 50.What is the probability that a student uses fewer than 400 minutes?

A call center receives calls from customers at a rate of 2 per min.The time between customer calls follows an exponential distribution. (a)What is the probability that it takes 1/3 of a minute or less between consecutive customer calls? (b)What is the probability that it takes 1/2 of a minute or more between consecutive customer calls?

A production process is known to produce a particular item in such a way that 5 percent of these are defective.If two items are randomly selected as they come off the production line,what is the probability that the second item will be defective?

A company is considering producing some new Gameboy electronic games.Based on past records,management believes that there is a 70 percent chance that each of these will be successful and a 30 percent chance of failure.Market research may be used to revise these probabilities.In the past,the successful products were predicted to be successful based on market research 90 percent of the time.However,for products that failed,the market research predicted these would be successes 20 percent of the time.If market research is performed for a new product,what is the probability that the product will be successful if the market research indicates a failure?

The joint probability of two or more independent events occurring is the sum of their marginal or simple probabilities.

The time required to travel downtown at 10 a.m.on Monday morning is known to be normally distributed with a mean of 40 minutes and a standard deviation of 5 minutes.What is the probability that it will take less than 35 minutes?

Machine breakdowns occur at a rate of 0.4 per week.The time between breakdowns follows an exponential distribution.What is the probability that more than 2 weeks go by without a breakdown?

Arrivals at a fast-food restaurant follow a Poisson distribution with a mean arrival rate of 16 customers per hour.What is the probability that in the next hour there will be exactly 8 arrivals?

The number of calls received by call center follows a Poisson process with a rate of 1.5 per minute.What is the probability that a minute goes by without a call?

List the two parameters of the normal distribution.

The number of phone calls coming into a switchboard in the next five minutes will either be 0,1,2,3,4,5,or 6.The probabilities are the same for each of these (1/7).If X is the number of calls arriving in a five-minute time period,what is the mean of X?

The use of "expert opinion" is one way to approximate subjective probability values.

The mean and standard deviation of the Poisson distribution are equal.

Suppose that,historically,April has experienced rain and a temperature between 35 and 50 degrees on 20 days.Also,historically,the month of April has had a temperature between 35 and 50 degrees on 25 days.You have scheduled a golf tournament for April 12.If the temperature is between 35 and 50 degrees on that day,what will be the probability that the players will get wet?

A consulting firm has received 2 Super Bowl playoff tickets from one of its clients.To be fair,the firm is randomly selecting two different employee names to "win" the tickets.There are 6 secretaries,5 consultants and 4 partners in the firm.Which of the following statements is not true?

Subjective probability implies that we can measure the relative frequency of the values of the random variable.

The F distribution is a continuous probability distribution that is helpful in testing hypotheses about variances.

When does P(A|B)= P(A)?

Saying that a set of events is mutually exclusive and collectively exhaustive implies that one and only one of the events can occur on any trial.