CK-12-Basic Probability and Statistics Concepts - A Full Course

3.5. Theoretical and Experimental Spinners http://www.ck12.org

We can see the result of each trial by choosing TABL, or pressing

GRAPH

.

And we see the graph of the resulting table, or go back to the first screen, simply by choosing GRPH, or pressing

GRAPH

again.

Now, the question asks how many times we landed on blue (number 1). We can actually see how many times we
landed on blue for these 20 spins. If you press the right arrow
(
I

)

, the frequency label will show you how many of the times the spinner landed on blue (number 1).

To go back to the question, how many times does the spinner land on blue if it is spun 20 times? The answer is 3.
To calculate the experimental probability of landing on blue, we have to divide by the total number of spins.

P(blue) =

3

20

= 0. 15

Therefore, for this experiment, the experimental probability of landing on blue with 20 spins is 15%.

Now let’s calculate the theoretical probability. We know that the spinner has 4 equal parts (blue, purple, green, and
red). In a single trial, we can assume that:

P(blue) =

1

4

= 0. 25

Therefore, for our spinner example, the theoretical probability of landing on blue is 0.25. Finding the theoretical
probability requires no collection of data.