In an article about the cost of health care, Money magazine reported that a visit to a hospital emergency room for something as simple as a sore throat has a mean cost of $328 (Money, January 2009). Assume that the cost for this type of hospital emergency room visit is normally distributed with a standard deviation of $92. Answer the following questions about the cost of a hospital emergency room visit for this medical service.
What is the probability that the cost will be more than $500? (to 4 decimals)
What is the probability that the cost will be less than $250? (to 4 decimals)
What is the probability that the cost will be between $300 and $400? (in inches, to 4 decimals)
If the cost to a patient is in the lower 8% of charges for this medical service, what was the cost of this patient's emergency room visit? (to 2 decimals) how do you get z= -1.40507? I can end up with the same answer for D with a calculator but I would like to know how you obtained this number so that i can do it by hand if calculator decides to not work.