1. Nile.com sells books online. In the long run, the average number of books boughtper

1. Nile.com sells books online. In the long run, the average number of books boughtper customer is 3.2 with a standard deviation of 2.1 and 41% of the customers buy3 or more books.

a. What is the probability that the average number of books bought by thenext 100 customers to shop at Nile.com will be less than 3.6?

b. What is the probability that the average number of books bought by thenext 100 customers to shop at Nile.com will be between 3.3 and 3.6?

c. What is the probability that more than 50% of the next 100 customers willbuy 3 or more books?


2. There are 200 students in a class. The average age is 23.4 with a standarddeviation of 4.8. 60 of the 200 students (or 30%) are over 30 years old. If Irandomly select 50 of the 200 students:

a. What is the probability the average age of the 50 students will be morethan 25?

b. What two ages symmetrically on either side of the average age is therean 82% chance that the mean of the sample of 50 students will fall
between?

c. What is the probability that less than 20% of the 50 students will bemore than 30 years old?

3. The average annual income in a small town is $32,145 with a standard deviationof $17,621. What is the probability that a person selected randomly from thetown will make more than $50,000?

4. I have a special die that has 2 sides with 2 dots each and 4 sides with 4 dots each.Each side is equally likely if I roll the die. What is the sampling distribution ofthe sample mean if I roll the die 2 times?