Exercises on General and Binomial Distributions

1. Which of the following variables is not discrete?

  The weight of a randomly selected cat.
  The number of cats in my office.
  The number of students in class today.
  The number of complete days until the end of the semester.

2. According to NCHS, in 1989 40.5% of persons 2 years of age and over were covered by private dental insurance. (Based on data from Vital and Health Statistics, Series 10, No. 183, "Dental Services and Oral Health: United States, 1989.") If 15 persons 2 years of age and over are randomly selected (from 1989), what is the probability that exactly 10 of them have private dental insurance?

  0.405.
  0.0001.
  0.973.
  0.027.

3. Which of the following experiments is not binomial?

   Rolling a pair of dice 10 times and determining the number of pips (little dots) that appeared.
  Tossing a biased coin 1000 times.
  Asking 20 people if they voted for Clinton in the 1996 presidential election.
  Surveying 90 people and asking them if they recogonize the McDonald's golden arches.

4. According to USA Today (12/08/96), 60% of Americans approved of the job President Clinton was doing. In a random sample of 15 Americans, what is the mean number of people who support the job the President is doing?

  The mean is 9 people.
  The mean is 1.90 people.
  The mean is 3.6 people.
  The mean is 15 people.

5. According to USA Today (12/08/96), 60% of Americans approved of the job President Clinton was doing. In a random sample of 15 Americans, what is the standard deviation for the number of people who support the job the President is doing?

  The standard deviation is 9 people.
  The standard deviation is 1.9 people.
  The standard deviation is 3.6 people.
  The standard deviation is 15 people.

6. According to USA Today (12/08/96), 60% of Americans approved of the job President Clinton was doing. In a random sample of 15 Americans, what is the probability that at least 10 disapprove of the job President Clinton is doing?

  P(at least 10) = 0.403.
  P(at least 10) = 0.033.
  P(at least 10) = 0.597.
  P(at least 10) = 0.967.

7. According to the National Center for Health Statistics, 33.3% of all adults are overweight. In a group of 40 adults, what is the mean number of overweight people.

  The mean is 3.0 people.
  The mean is 8.9 people.
  The mean is 13.3 people.
  The mean is 2.98 people.