Binomial Probabilty math Help please?

Question

I got the anwsers but i need to make sure they are right
1. How many ways can 8 different test questions be arranged on an exam?
8 factorial check…..40320

2. One of the telephone number prefixes in Missoula is 728. How many different phone numbers beginning with 728 are possible?
10^4 10,000

3. In a group of scientists selected for astronaut training, there are 15 men and 4 women.
Of this group, only four are to be chosen for training. If exactly one man and three
women are chosen, how many different selections are possible?
4’3’2’15= 360 ways

4. A lottery has one first prize of $5000, two second prizes of $1000, and two third prizes
of $100. If 10,000 tickets are sold for $1, what are the expected winnings of a person
buying one ticket?
-.28

9. A certain state issues license plates where the the first three characters are letters of the alphabet and the remaining three characters are numbers 0 through How many different license plates are possible? 17576000

Answer 1

Q 3. is wrong
men ........................women
15 choose 1 and 4 choose 3
15 C 1 X 4 C 3
15*4
60

All the rest correct.

Answer 2

In #3, 15 ways to choose the guy, 4 ways to choose the group of women, that's 60 difference selections, not 360.

Answer 3

Your answers all look right to me.

Thanks for doing them yourself first and looking for validation instead of expecting someone here to just do the work for you!