Video Transcript
A number is chosen at random from
the set three, four, seven, eight. What is the probability that the
number is even?
We’re told that this number is
going to be chosen at random, which means that every number in the set has an equal
chance of being chosen. When all outcomes of an experiment
are equally likely, the probability of a particular event occurring is found by
dividing the number of successful outcomes by the total number of outcomes.
Successful outcomes are those that
mean the event has occurred, which in this example would be the even numbers in the
set. There are four numbers in the set,
so this is the total number of outcomes. Two of the numbers, four and eight,
are even. Hence, the probability of choosing
an even number is two over four. This fraction can of course be
simplified to one-half. There are the same number of even
and odd numbers in the set. So it makes sense that the
probability of choosing an even number at random is one-half.
