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7th Grade Math / Lesson 9B: Compound Events

COMPOUND EVENTS
What will we be learning in this lesson?


  • In this lesson you will use a sample space to determine probability.
Vocabulary words are found in this purple color throughout the lesson. Remember to put these in your notebook.


COMPOUND EVENTS


  • Probability:       desired outcome
                      total outcomes (sample space)

  • Sample space: total number of outcomes for an event

  • Compound events: more than one event in the problem


COMPOUND EVENTS


Determine the sample space for the following compound event. Use the sample space to answer the probability questions.

In the previous section we looked at the sample space for picking 2 items, one from each box.

Red, 1 blue, 1 green, 1 white, 1
Red, 2 blue, 2 green, 2 white, 2
Red, 3 blue, 3 green, 3 white, 3

1. What is the probability of choosing the color red and the number 3?

Remember, probability is the desired outcome over the total outcomes. The desired outcome is red, 3. How many do you see in the list? Just 1. So there is 1 desired outcome. How many total? 12 Which means that the probability of choosing red, 3 is  1/12


COMPOUND EVENTS


Red, 1     blue, 1     green, 1     white, 1
Red, 2     blue, 2     green, 2     white, 2
Red, 3     blue, 3     green, 3     white, 3

2. What about the probability of choosing the color green or the number 1?

How many ways can you choose a green?

How many ways can you choose a 1?


COMPOUND EVENTS


Red, 1     blue, 1     green, 1     white, 1
Red, 2     blue, 2     green, 2     white, 2
Red, 3     blue, 3     green, 3     white, 3

2. What about the probability of choosing the color green or the number 1?

How many ways can you choose a green? 3

How many ways can you choose a 1?    3 because green,1 is already counted as picking a green. You can not count it twice.
So there are 6 desired outcomes and 12 total outcomes. The probability of picking a green or a 3 is
6/12  which is equal to 1/2(.5 or 50%)


  • Can you use a sample space to determine probability?
  • Go back to the classroom to get to your homework and any other items you need to attend to.