http://www.ck12.org Chapter 3. Introduction to Discrete Random Variables
Example C
You are spinning a spinner like the one shown below 170 times. How many times does it land on blue? Does the
experimental probability get closer to the theoretical probability? How many times do you predict we would have to
spin the spinner to have the experimental probability equal the theoretical probability? Simulate the spinning of the
spinner using technology.
With 170 spins, we get a frequency of 42 for blue.
The experimental probability in this case can be calculated as follows:
P(blue) =42
170
= 0. 247
Therefore, the experimental probability is 24.7%, which is even closer to the theoretical probability of 25%. While
we’re getting closer to the theoretical probability, there is no number of trials that will guarantee that the experimental
probability will exactly equal the theoretical probability.
Guided Practice
You are spinning a spinner like the one shown below 500 times. How many times does it land on blue? How does
the experimental probability of landing on blue compare to the theoretical probability? Simulate the spinning of the
spinner using technology.