### For a certain kind of cancer operation the probability that a patient will die within a month is 18%. Four such operations were accomplished on one day.Let the random variable be the number of patients not dying within one month. Draw the probability density function and the cumulative distribution function. Determine the expected value and the variance.

### Homework 3:

### The probability that a randomly chosen sales prospect will make a purchase is 0.7. A salesperson talks to five prospects.

### 1. What is the probability that he will make exactly four sales?

### 2. What is the probability that he will make up to four sales?

### 3. What is the expected number of sales?