In the above table households are classified according to

Question

Purchase Behavior for Big-Screen Televisions

Planned To Purchase	Actually Purchased
	Yes	No	Total
Yes	200	50	250
No	100	650	750
Total	300	700	1000

In the above table, households are classified according to whether they planned to purchase and whether they actually purchased big-screen televisions.  Draw the Decision Tree for this example.

Purchase Behavior Regarding Plasma Screen Televisions and DVR.

Purchased Plasma Screen	Purchased DVR
	Yes	No	Total
Plasma Screen	38	42	80
Not Plasma Screen	70	150	220
Total	108	192	300

1. Using the cross-classified data above, construct the decision tree. Use your Decision Tree to find the probability that a household purchased a DVR, given that the household purchased a plasma-screen television.

(Note: the probability formulas for question 2 are listed below)

The probability of A given B is equal to the probability of A and B divided by the probability of B. 

P(A/B) = P(A and B)/P(B) 

The probability of B given A is equal to the probability of A and B divided by the probability of A.

P(B/A) = P(A and B)/P(A)

Where:

P(A and B) = joint probability of A and B

P(A) = marginal probability of A

P(B) = marginal probability of B