Tips A waiter believes the distribution of his tips has a model that is slightly skewed to the right, with a mean of $9.60 and a standard deviation of $5.40.  a) Explain why you cannot determine the...

Tips A waiter believes the distribution of his tips has a model that is slightly skewed to the right, with a mean of $9.60 and a standard deviation of $5.40.

 a) Explain why you cannot determine the probability that a given party will tip him at least $20.

 b) Can you estimate the probability that the next 4 parties will tip an average of at least $15? Explain.

 c) Is it likely that his 10 parties today will tip an average of at least $15? Explain.