SOLUTION: i've tried answering this, but i don't know where to start. The probablity that a door-to door salesman convinces a customer to buy is 0.65. Assume that the sales are independen

Algebra ->  Probability-and-statistics -> SOLUTION: i've tried answering this, but i don't know where to start. The probablity that a door-to door salesman convinces a customer to buy is 0.65. Assume that the sales are independen      Log On


   



Question 199498: i've tried answering this, but i don't know where to start.
The probablity that a door-to door salesman convinces a customer to buy is 0.65. Assume that the sales are independent find the probability that the salesman makes a sale before reaching the fifth house.

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


This is one where it is much simpler to calculate the probability of the event that is opposite to the desired event. First of all, "Before the fifth house..." means that he will make a sale while visiting houses number 1 through 4.

If he has a 0.65 probability of making a sale, then there is a 1 - 0.65 = .35 chance that he will NOT make a sale at any given house. Making a sale at at least one of the first four houses is 1 minus the probability that he makes no sales at all at the first four visits, so:



Therefore the probability that you are looking for is:



You get to do your own arithmetic.

John