3. A waiter believes the distribution of his tips is slightly skewed to the right, with mean of $9.60 and a standard deviation of $5.40. a) Explain why you can't determine the probability that a given party will tip him at least $15? b) The waiter usually waits on 40 parties over a weekend of work. Find the probability that he will earn at least $500 in tips. Round your z-scores to 2 decimal places during your calculations, then round probability answers to 4 decimal places