Exam 4: Discrete Random Variables

A courier company has established a record in a major city for delivering 90% of its packages the next working day. -Of the eight,what is the average number you expect to be delivered the next day?

The variable "employment status" which can take on one of two values: 1 for "employed" and 0 for "unemployed" is and example of a(n)_____________ random variable.

The equation for the variance of the binomial distribution is given by:

An archer has a probability of 0.95 of hitting a target.If the result of each attempt is independent,what is the probability he/she will miss the target for the first time on the 15^th shot?

If the number of surface nonconformities on a specific size of metal piece is the discrete random variable in question,then the appropriate probability distribution that can describe the probability of a specific size metal sheet containing 3 defectives is given most likely by ___________________ distribution.

A test has 6 multiple choice questions,each with 4 alternatives.What is the probability of guessing 5 or more questions correctly?

If X has the probability distribution

Find the probability of more than 7 customers arriving within a minute.

A discrete variable that can often be used to describe the number of occurrences of an event over a specified interval of time or space is a(n)_____ random variable.

The J.O. Supplies Company buys calculators from a foreign supplier. The probability of a defective calculator is 10%. -If 3 calculators are selected at random,what is the probability that exactly one of the calculators will be defective?

A courier company has established a record in a major city for delivering 90% of its packages the next working day. -What is the probability that the number of delivered will be within 2 standard deviations of the mean?

A large disaster cleaning company estimates that each of the jobs it bids on are finished within the bid time with probability 0.3 independent of each other job it bids on. Consider a random sample of 8 jobs that is has contracted. -What is the probability that exactly 4 of the jobs were not completed within the bid time?

A fair die is rolled 10 times.What is the average number of even number (2,4,or 6)outcomes?

In a binomial distribution the random variable X is continuous.

What is the probability that there will be a total of 7 defects on four standard sheets of steel?

A local bank has determined that the number of companies listed in the area declaring bankruptcy follows an approximately a Poisson distribution with a mean of 2.6 per year. -Find the probability that exactly 4 bankruptcies occur next year.

The manager of the local grocery store has determined that, on the 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 no more than 2 customers use the service desk?

A discrete random variable may assume a countable number of outcome values.

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?

According to data from a federal blood program, 40% of all individuals have type A blood. If six individuals give blood, find the probability -Find the mean number of individuals having group A blood.