1. If 8 books are arranged on a shelf, what is the probability that 3 particular
books are together?

1. If 8 books are arranged on a shelf, what is the probability that 3 particular
books are together?

DICTIONARY
Combinations (the "Choose" Formula)
A permutation is an ordered arrangement of objects.
On the calculator ...
Press: [MATH]
n is the number of objects available to [<] (Prb)
be arranged r is the number of objects [3] (nCr)
that are being arranged.
Examples:
How many different 5 person teams There are 15 people on the studentscouncil.
can be made from 10 people? How many 3 person subcommittees can be
made on the council?

2. (a) How many numbers of 5 different digits each can be formed from the
digits 0, 1, 2, 3, 4, 5, 6?
(b) If one of these numbers is randomly selected, what is the probability
it is even?
(c) What is the probability it is divisible by 5?

There are 10 football teams in a certain conference. How many games must be
played if each team is to play every other team just once?

Seven people reach a fork in a road. In how many ways can they continue
their walk so that 4 go one way and 3 the other?