Chapter 1.6 Probability

Objective: Students set up probability equations appropriately

Experimental Probability

Probability of event =

Number of times event occurs

Number of trials

Example 1

A player hit the bull’s eye on a circular dartboard 8 times out of 50. Find the experimental probability that the player hits the bull’s eye.

We need to use the formula.

Number of times event occurs =

Number of trials

816%

50

Example 2

Find the theoretical probability of rolling a multiple of 3 with a number cube? How about rolling an odd?

The Cube is a normal six sided di.

A) How many numbers on the cube are a multiple of 3? Yes 2 numbers, 3 and 6.

So we get… 2 = 1 6 3 B) How many numbers are odd?

Yes 3 numbers, 1,3,5

So we get… 3 = 1 6 2

Example 3 Suppose that all the points on the circular

dartboard shown below are equally likely to be hit by a dart you have thrown. Find the probability of only scoring 2 points with one throw.

Note: The radius of each circle is one unit larger than the one below it. 2020

1052

Experimental Probability

First we need to find the area of the whole dart board. This is the denominator because any throw can hit any where on the dart board.

To find the area of the green we need to subtract the areas of the others. So we get (using area πr2 of a circle)

π(4r)2 – π(3r)2

π(4r)2

= 16πr2 - 9πr2

16πr2 = 7πr2 16πr2

202010

52

7

16

P. 42 (1- 19) oddOmit 3 and 5