SHOW WORK I DO NOT UNDERSTAND

5. A waiter estimates that his average tip per

table is $20 with a standard deviation of $4. If

we take samples of 9 tables at a time, calculate

the following probabilities when the tip per table

is normally distributed.

a. What is the probability that the average

tip for one table is less than $21?

b. What is the probability that the average

tip for one table is more than $21?

c. What is the probability that the average

tip for one table is between $19 and $21?

12. In a large population, 76% of the households

own microwaves. A simple random sample of

100 households is to be contacted and the sample

proportion computed. What is the mean and

standard deviation of the sampling distribution of

the sample proportions?