For #38, draw the tree diagram as was drawn in class.

Thought process:

This is the conditional probability since it ask for given that :...........

Conditional prob. 

First, given it is red

P(R2/R1) = P( R2 and R1) /  P(R1)

Second scenerio, given it is white

P(R2/W1) = P(R2 and W1) / P(W1)

Since this is a dependent event we have:

P(R2 and R1) = P(R1) •P(R2/R1)

P(R2 and W1) = P(W1)  • P( R2/W1)

In essence, the question ask for drawing a red ball on the second draw.

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Therefore:

P(R2) = (2/7) (2/7) + (5/7) (2/7) = 2/7

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For part B.  draw the tree as it was drawn in class.

same thought process as it was in part a.

P(R2) = (2/7)(1/6) + (5/7) (2/6) = 2/7

Now, try to ponder why is the answer the same?  Try to make up your own tree and answer the question as it was in #38.

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