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2. Fix-It Copiers advertises a mean time of 100 minutes for office calls with a standard deviation of 25 minutes. Assuming that the repair time is normally distributed, what percentage of calls are completed: a) Between 100 and 120 minutes? (28.81%) b) In less than 120 minutes? (78.81%) c) In less than 60 minutes? (5.48%) d) (it is not included for stat 1012, Fall 2020) Twenty percent of their jobs take more than how much time? (121 minute)

3. The weight of potato chips in a medium-size bag is stated to be 10 ounces. The amount that the packaging machine puts in these bags is believed to have a normal model with a mean of 10.1 ounces and a standard deviation of 0.05 ounces. a) What is the probability that the weight of a randomly selected bag is less than 9.95 ounces? (0.0013) b) What is the probability that the weight of a randomly selected bag is between 10 and 10.1 ounces? (0.4772) c) What fraction of all bags sold are underweight? (0.0228)

4. The marks on a statistics test are normally distributed with a mean of 78 and a standard deviation of 6. a. What proportion of the class has a test mark of less than 75? (0.3085) b. (it is not included for stat 1012, Fall 2020) What is the probability that a class of 50 has an average test mark that is less than 75? (0)