1. The IT manager at a large company has developed the following probability distribution for the number of interruptions per day.

(a) What is the expected number of interruptions per day?

(b) What is the standard deviation in the number of interruptions per day?

2. An important part of customer service responsibilities for a cable company relates to the speed with which troubles in residential service can be repaired. Suppose that past data indicate that the likelihood is .80 that troubles in residential service can be repaired on the same day. Out of the next 12 residential repair calls received,

(a) What is the probability that exactly 10 will be repaired the same day?

(b) What is the probability that at most 10 will be repaired the same day?

(c) How many would you expect to be repaired the same day?

(d) What is the standard deviation in the number who will be repaired the same day?

3. Suppose that job satisfaction scores for airline industry employees are approximately normally distributed with a mean of 100 and standard deviation of 15.

(a) What percentage of airline industry employees has job satisfaction scores above 90?

(b) What percentage of airline industry employees has job satisfaction scores between 90 and 120?

4. According to a recent survey by the National Retail Federation, men spent an average of $135 on Valentine's gifts. Assume the standard deviation for this population is $40. If a random sample of 60 men who celebrate Valentine's Day is selected,

(a) What is the probability that the sample mean will be below $200?

(b) What is the probability that the sample mean will be between $130 and $200?

5. The Social Media and Personal Responsibility Survey found that 69% of parents are "friends" with their children on Facebook. Suppose a random sample of 140 parents is selected.

(a) What is the standard error of the proportion?

(b) What is the probability that, in this sample, between 60% and 75% of the parents is "friends" with their children on Facebook?