Question 937704: Suppose you have 33 girls and 28 boys in a classroom. You put each of their names on a piece of paper and put the papers in a hat.
4. Without looking, how many names would you need to pull out of the hat to be sure you get two girls?
I have tried 2,3,4,16,17
5. Without looking, how many names would you need to pull out of the hat to be sure you get either two boys or two girls?
I have tried 4,6,8,30,32
Answer by Edwin McCravy(20060)   (Show Source):
You can put this solution on YOUR website!
4. Think of the worst possible situation. It's unlikely but possible for you
to pull out all 28 boys' names in a row, one by one. Then there would be
no more boys'; names in the hat. So the next 2 names you would pull out
MUST be girls' names. So if you pull out 30 names, you are certain that at
least 2 of them MUST be girl's names. So in the worst possible case you would
have 28 boy's names and 2 girl's names.
Answer: 30
----------------------------------------------
5. You only need to pull out 3 for there are only two sexes, so there must be
two of one sex among the three. They are either 3 of the same sex or two on
one sex and 1 of the other. So with only 3 names you can be sure of having
2 boys' names or 2 girls' names.
Answer: 3
Edwin
|
|
|
