1. A sales person makes 15 sales calls a day. If the probability of closing a sale is 40%, what is the probability that the sales person will close at least 8 sales?

a. 0.095

b. 0.213

c. 0.787

d. 0.905

2. Suppose that the fill amount of bottles of soft drink has been found to be normally distributed with a mean of 2.0 liters and a standard deviation of 0.15 liters. Bottles that contain less than 92.5% of the listed net content (i.e. 1.85 liters) can result in the manufacturer being subject to a penalty by the state office of consumer affairs, whereas bottles that have a net content above 2.18 liters may cause excess spillage upon opening. What percentage of bottles will be out of the specification that a bottle should have at least 1.85 liters but no more than 2.18 liters?

a. 15.9%

b. 27.4%

c. 88.5%

d. 0%, all bottles should be within specs

3. The acceptable time for answering the phone at a call center is 25 seconds. In a sample of 600 calls, 240 were answered within 25 seconds. With 95% confidence level we can say that the true proportion of calls that are answered within 25 seconds is

a. Between 39% to 41%

b. Between 38% to 42%

c. Between 36% to 44%

d. Between 34% to 46%

4. Which of the following is the best definition for the significance level, alpha, which is used in hypothesis testing?

a. Alpha is the probability that H0 is not rejected, when H0 is true

b. Alpha is the probability that H0 is rejected, when H0 is true

c. Alpha equals one minus beta

d. Alpha is the probability that random variation could cause a sample to appear at least as far from H0 as the observed data, when H0 is true.