Question 1042771:  A salesperson has a policy of calling upon a customer a second time if she does not make the sale on the first call, and trying a third time, and last time if she fails on the first two calls. She has a probability of a sale on the first call of 0.3. If she fails on the first call, the probability of a sale on the second call is 0.2. If the first two calls are unsuccessful, her probability of success on the third call is only 0.1. 
how i want do tree diagram for this question? 
 Answer by mathmate(429)      (Show Source): 
You can  put this solution on YOUR website! Question: 
A salesperson has a policy of calling upon a customer a second time if she does not make the sale on the first call, and trying a third time, and last time if she fails on the first two calls. She has a probability of a sale on the first call of 0.3. If she fails on the first call, the probability of a sale on the second call is 0.2. If the first two calls are unsuccessful, her probability of success on the third call is only 0.1. 
how i want do tree diagram for this question? 
  
Answer: 
The tree diagram is shown below. 
It is as important to understand how to interpret a tree-diagram as to draw it. 
The probability of failure is the product of probabilities of all three steps, namely 
P(failure)=0.7*0.8*0.9=0.504 
The probability of success, however, is the sum of three possible cases, depending on the number of calls made. 
P(success on first call)=0.3=0.300 
P(success on second call)=0.7*0.2=0.140 
P(success on third call)=0.7*0.8*0.1=0.056 
So total probability of success 
P(success)=0.300+0.140+0.056=0.496 
which is complementary to P(failure), or 
P(success)+P(failure)= 1.000 
is a good check for the ansewr. 
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