Adding probabilities

The first instance of  is under the Probability and statistics Math Mission. This exercise deals with the addition property of addition, including the concern of overlapping events.

Types of Problems
There are two types of problems in this exercise:


 * 1) Use chart: This problem describes a situation and provides a chart of the sample space of all outcomes. The student is asked to correctly answer a question about an 'or' probability.Addprob1.png
 * 2) Use information: This problem describes in words a situation with overlapping events. The student is asked to answer four questions which lead through the step-by-step process to find an 'or' probability.Addprob2.png

Strategies
This exercise is medium to get accuracy badges, especially if probability rules are something that are new to you. The speed badges are medium because once you get into the right rhythm you can solve these the same way repeatedly, it really depends on how fast you can type!


 * 1) On Use chart we are not kidding, just use the chart. It lists the possibilities and you can count them to find the answer
 * 2) On Use information a Venn Diagram can be used to make the answers very simple.
 * 3) As a general rule, in case it was not known, the general addition rules for probability is $$ P(A or B)=P(A)+P(B)-P(A and B) $$.