Probability, Normal and Poisson Distributions, Mean and Standard Deviations

(31) The sales records of a real estate agency show the following sales over the past 200 days:

Number of Number
Houses Sold of Days
0 60
1 80
2 40
3 16
4 4

What is the probability of selling at least 2 houses over the past 200 days?
a. .10
b. .20
c. .30
d. .70
e. .90 ____________

(32) Sweetwater & Associates write weekend trip insurance at a very nominal charge. Records show that the probability that a motorist will have an accident during the weekend and file a claim is 0.0005. Suppose they wrote 400 policies for the coming weekend. What is the probability that more than one claim will be filed?

a. 0.8187
b. 0.1637
c. 0.0176
d. 0.0160
e. None of the above ____________

(33) The production department has installed a new spray gun to paint automobile doors. As common with most spray guns, unsightly blemishes often appear because of improper mixture or other problems. The average number of blemishes is 0.5 per door. If the distribution of blemishes follows a Poisson distribution, out of 10,000 doors painted, about how many would have no blemishes?
a. About 7,093
b. About 6,065
c. About 3,935
d. About 1,023
e. None of the above ____________

(34) The main computer used by a company for inventory and payroll crashes, on average, once a week. What is the probability that the time between the next two crashes will be less than two weeks?
a. 13.57%
b. 23.33%
c. 77.67%
d. 86.47%
e. None of the above ____________

(35) The mean score of a college entrance test is 500; the standard deviation is 75. The scores are normally distributed. What percent of the students scored below 320?
a. About 12.82%
b. About 4.14%
c. About 1.86%
d. About 0.82%
e. None of the above

(23) A population consists of all defensive tackles on Sociable University's football team. Their weights (in pounds) are as follows: 204; 215; 207; 212; 214 and 208. What is the standard deviation (in pounds)?
a. About 100
b. About 16
c. About 6
d. About 4
e. None of the above (what is the exact answer??)