19. In how many different ways can a work party of 3 be chosen from 8 volunteers?

A. 3 B. 24 C. 336D. 56E. None of the above

20. Which of the following is/are properties of the Binomial Distribution?

A. The number of trials is fixed in advance. B. The trials are independent. C. Each trial has exactly two outcomes. D. The probability of success is the same for each trial. E. All of the above.

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21.Find the probability of at most 2 girls in 6 births. Assume that male and female births are equally likely and that the births are independent events.

A. 0.234 B. 0.109 C. 0.333 D. 0.657 E. 0.344

22.A test consists of 10 true/false questions. To pass the test a student must answer at least 8 questions correctly. If a student guesses on each question, what is the probability that the student will pass the test?

A. 0.011. B. 0.044.C. 0.055.D. 0.800. E. none of the above

23. The number of armed robberies and their probabilities, in a particular city in any given month, are given in the table below:

Number of armed robberies Probability 1 0.05 2 0.30 3 0.40 4 0.25

How many armed robberies on the average should be expected on a typical month?

A. 5.00 B. 2.50 C. 2.85D. 3.01 E. None of the above

24. Find the standard deviation of the above distribution.

A. 0.73 B. 0.77 C. 0.80 D. 0.85E. None of the above