# Statistics: normal probability, binomial & poisson probability distribution

1. If the variance of a probability was computed to be 3.6 grams, what is the standard deviation?
a. 0.6
b 1.9
c 6.0
d 12.96
e none of the above

2. on a very hot summer day, 5 percent of the production employees at midland states steel are absent from work. The production employees are to be selected at random for a special in-depth study on absenteeism. What is the probability of selecting 10 production employees at random on a hot summer day and finding that none of them are absent?
A 0.002
B 0.344
C 0.599
D 0.100
E none of the above

3. the marketing department of a nationally known cereal maker plans to conduct a national survey to find out whether or not consumers of flake cereals can distinguish one of their favorite flake cereals. To test the questionnaire and procedure to be used, eight persons were asked to cooperate in an experiment. Five very small bowls of lake cereals were placed in front of a person. The bowls were labeled a, b, c, d, and e. the person was informed that only one bowl contained his or her favorite flake cereal. Suppose that the eight persons in the experiment were unable to identify their favorite cereal and just guessed which bowl it was in. what is the probability that one of the eight guessed correctly?
A 0.168
B 0.009
C 0.788
D 0.125
E none of the above

4. in which of the following discrete distribution does the probability of a success vary from one trail to the next?
A binomial
B poisson
C hypergeometric
D all of the above
E none of the above

5 david's gasoline station offers 4 cents off per gallon if the customer pays cash and does not use a credit card. Past evidence indicates that 40% of all customers pay in cash. During a one hour period twenty-five customers buy gasoline at this station. This situation is an example of what type of discrete probability distribution?
A continuous probability distribution
B poisson probability distribution
C binomial probability distribution
D hypergeometric probability distribution
E none of the above

Question 6-11
A sample of 500 evening students revealed that their annual incomes from employment in industry during the day were normally distributed with a mean income of \$30,000 and a standard deviation of \$3000.

6. how many students earned more than \$30,000
a 175
b 410
c 285
d 360
e 250

7 how many students earned between \$27,000 and \$33,000
a 143
b 341
c 215
d 710
e 417

8 how many students earned between \$24,000 and \$30,000
a 934
b 304
c 293
d 149
e 239

9 how many students earned between \$20,000 and \$40,000
a 500
b 400
c 914
d 516
e 308

10 how many students earned less than \$22,500
a 4
b 13
c 2
d 15
e 3

11 how many students earned more than \$36,000
a 15
b 13
c 11
d 19
e 22

Question 12-13 (Binomial Probability Distribution)
Eighty percent of trees planted by woodlands conservation group survive. What is the probability that:

12. 10 of the 12 trees just planted will survive?

13. at least 10 of the trees just planted will survive?

14. (Poisson Probability Distribution)
customers use an automatic teller machine at an average rate of 15 per hour. What is the probability that exactly 12 will use the machine in the next hour?