QNT 275T Week 3 Case Study

1) For a binomial process, the probability of success is 40 percent and the number of trials is 5. Find P(X ≤ 1).

❏ .0870

❏ .2592

❏ .0778

❏ .3370

2) A continuous probability distribution that is useful in describing the time or space between successive occurrences of an event is a(n)

❏ uniform probability distribution.

❏ normal probability distribution.

❏ Poisson probability distribution.

❏ exponential probability distribution.

3) The life of a light bulb is exponentially distributed with a mean of 1,000 hours. What is the probability that the bulb will last less than 800 hours?

❏ .6321

❏ .5507

❏ .7135

❏ .4493

4) An important part of the customer service responsibilities of a cable company is 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?

❏ .0010

❏ .6328

❏ .9990

❏ .2373

5) For a binomial process, the probability of success is 40 percent and the number of trials is 5. Find the variance.

❏ 5.0

❏ 1.2

❏ 2.0

❏ 1.1

6) If the random variable x is normally distributed, ______ percent of all possible observed values of x will be within three standard deviations of the mean.

❏ 68.26

❏ 95.44

❏ 99.73

❏ 100

❏ None of the other choices is correct.

7) Given that the length an athlete throws a hammer is a normal random variable with mean 50 feet and standard deviation 5 feet, what is the probability he throws it between 50 feet and 60 feet?

❏ .9972

❏ .5000

❏ .9544

❏ .4772

8) Employees of a local university have been classified according to gender and job type.

If an employee is selected at random, what is the probability that the employee is a member of the hourly staff, given that the employee is female?

❏ 0.400

❏ 0.133

❏ 0.160

❏ 0.053

❏ 0.533

9) Consider a Poisson distribution with an average of 3 customers per minute at the local grocery store. If X = the number of arrivals per minute, find the probability of more than 7 customers arriving within a minute.

❏ .0216

❏ .0081

❏ .0108

❏ .0118

10) If the mileage per gallon for a car is normally distributed, 32 mpg has a z score of 1.2, and 24 mpg has a z score of −.4, what is the mean mpg of the distribution?

❏ 28

❏ 26

❏ 30

❏ 38