Thread: Combinations

Just some questions I'd like confirmation on thanks!

1. A group of nine children visit Santa’s grotto. Three of the children
are two years of age and the remaining six are three. Santa has a
sack that contains twenty wrapped presents. Twelve of these are
suitable for children of all ages. The other eight are only suitable
for children older than two. Santa draws one present at random
from his sack for every child.
(a) What is the probability that all three of the two-year olds get
presents that are suitable for their age group?
[5 marks]
(b) Given that all children got presents that are suitable for their
age group, what is the probability that all of the three-year
olds got presents that are suitable for children older than two?
[6 marks]
(c) What is the probability that all of the children get presents
that are suitable for all ages?
[6 marks]
(d) What is the probability that exactly six of the nine children
received presents that are suitable for all ages?
[6 marks]

How many different combinations can I make with these numbers?




bar stool