A waiter believes the distribution of his tips has a model that is slightly skewed to the left, with a mean of $9.40 and a standard deviation of $4.20. He usually waits on about 40 parties over a weekend of work a) Estimate the probability that he will earn at least $400. b) How much does he earn on the best 1% of such weekends? a) P(tips from 40 parties > $400) = (Round to four decimal places as needed.) b) The total amount that he earns on the best 1% of such weekends is at least $ (Round to two decimal places as needed.)