Video Transcript
What is the probability of rolling
a number greater than or equal to four on a fair die?
We begin by recalling that a
regular fair die has six faces numbered from one to six. This means that when we roll the
die, there are six possible outcomes. In this question, we are interested
in the event of rolling a number greater than or equal to four. There are three ways of satisfying
this, rolling a four, rolling a five, or rolling a six. We recall that we can write the
probability of an event as a fraction, where the numerator is the number of
favorable outcomes and the denominator the total number of possible outcomes.
In this question, the probability
of rolling a number greater than or equal to four is three out of six or
three-sixths. Since the numerator and denominator
are divisible by three, we can simplify this fraction. And we can therefore conclude that
the probability of rolling a number greater than or equal to four on a fair die is
one-half. It is worth noting that we could
also write our answer as a decimal or percentage. One-half is equal to 0.5 and 50
percent.
