Lesson 3

In Discover, you determined that in dependent events, the probability of the second event is influenced by the probability of the first event. This probability is considered to be conditional.

 

You can also have more than one event happening at the same time. Let’s investigate how to calculate the probability of two dependent events.

 

Try This 3

 

From Discover, you learned that when the marble was not replaced, the probability of the second event happening was directly affected and that the events were considered to be dependent. Use Compound Independent and Dependent Events to investigate how the probability of dependent events is calculated.

 

 

Start with a bag that contains three blue and four green marbles. Draw two marbles from the bag, one at a time. Each marble is not replaced in the bag after it is drawn. Then complete the activity using two blue marbles and seven green marbles in the bag. Do not replace marbles.

1. Using the applet, determine the calculation to find the probability of each outcome. Record your results in a chart like the following.
   
   

   Experiment	Outcome	Calculation
   three blue marbles and four green marbles	BB
   	BG
   	GB
   	GG
   two blue marbles and seven green marbles	BB
   	BG
   	GB
   	GG

2. How does the probability that the first event will occur directly affect the probability that the second event will occur? Explain.
3. Develop a general formula to find the probability for picking two blue marbles without replacing the first after it is drawn.
4. Explain why the probability of the second event is considered to be conditional.

Save your responses in your course folder.

 

Share 2

 

With a partner or in a group, compare the general formula that you created for question 3 of Try This 3. Come to an agreement on a general formula; then return to the applet and test the formula using a bag of two blue marbles and five green marbles.

 

If required, save a copy of your discussion in your course folder.