7) The time it takes for a statistics professor to grade an exam is normally distributed with a mean of 9.7 minutes and a standard devation of 1.9 minutes. There are 50 students in the professor's class. What is the probabilty that more than 8 hours are needed to grade all of the exams? (Report your answer to 4 decimal places.)

8) The daily productivity of a factory worker is normally distributed with a mean of 100 units and a standard deviation of 22 units. What is the probability that the average number of units produced in one day by 9 randomly selected workers is less than 90 units? (Report your answer to 4 decimal places.)

9) A coffee shop in a large office building provides coffee for the occupants in the building. The coffee shop manager has determined that the mean number of cups of coffee an employee consumes in a day is 2 with a standard deviation of 0.9. A new business that has located in the building intends to have 150 new employees. What is the probability that the new employees will consume more than 285 cups of coffee per day? (Report your answer to 4 decimal places.)

10) The number of hamburgers consumed per month by undergraduate students is normally distributed with a mean of 8.5 and a standard deviation of 1.75. What is the probability that in a random sample of 28 students more than 231 hamburgers are consumed? (report your answer as a decimal to 4 decimal places)

11) A pharmaceutical manufacturer of aspirin claims that the proportion of headache sufferers who get relieve with two aspirins is 66%. What is the probability that in a random sample of 250 headache sufferers, more than 70% obtain relief? (Report your answer to 4 decimal places.)

12) Using the aspirin problem above, what if the probability if the sample is increased to 1000? (Report your answer to 4 decimal places.)
please explain how to do this in excel along with the answers.