Use the following scenario for the next 3 questions. Suppose that monthly sales volume for a product is normally distributed, with a mean of 500 units and a standard deviation of 50 units. If x denotes the number of units sold in a month, what are the following probabilities? 
1) P(x < 450) 
2) P(x > 600) 
3) P(400 < x < 450)
The next 2 questions refer to the following situation. Between the hours of 1:00 and 5:00 PM the average number of phone calls per minute on a cell phone tower is 2.5.
4) What is the probability that during one particular minute there will be more than 6 phone calls?
5) What is the probability that during one particular minute there will be less than 5 phone calls?The next 2 questions refer to the following scenario. Consider an experiment of flipping a fair coin 50 times. Assign a random variable x, where the value of x is equal to the number of heads observed in the flips.
6) What is the probability of observing 30 or more heads in 50 flips?
Use the following scenario to answer the next 3 questions. Suppose a student in Business Statistics has not been attending class this quarter but decides to take the exam anyway. If he randomly guesses on each of the 20 questions, then he has a 1 out of 5 chance of getting a correct answer, since it is multiple choice exam with choices a, b, c, d, or e.
8) How many questions should the student expect to get correct on this exam?
9) What is the probability that the student will get a “C” or better, which is 14 or more correct?
10) What is the probability that the student will score lower than a “C” (13 or less correct)?