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In each problem, (a) identify the distribution, including the values of all para

ID: 3179839 • Letter: I

Question

In each problem, (a) identify the distribution, including the values of all parameters, and (b) find the answer, to 4 decimal places.

5. A salesman notes that his success rate is about 10%. If he has 25 customers, and assuming independence, find the probability that he makes exactly 3 sales. A: B:

6. A batch of 20 computer monitors contains 4 defective ones. If you randomly select 5 monitors and test them, find the probability that you find at least one of the defective monitors. A: B:

7. Suppose that the expected number of customers at a convenience store is 6 every 20 minutes. In a given 20-minute time period, find the probability of having exactly 5 customers. A: B:

8. Find the probability that an investor makes a profit on 7 of her next 10 investments, assuming independence and a 0.6 chance of making a profit each time. A: B:

Explanation / Answer

5. A salesman notes that his success rate is about 10%. If he has 25 customers, and assuming independence, find the probability that he makes exactly 3 sales.

a. The binomial distribution describes the behavior of a count variable X if the following conditions apply:

1: The number of observations n is fixed.
2: Each observation is independent.
3: Each observation represents one of two outcomes ("success" or "failure").
4: The probability of "success" p is the same for each outcome.

So all the above conditions are satisfied, so this is binomial distribution.

b. Here p=0.10 and n=25

We need to find P(x=3)=ncx*p^x*(1-p)^n-x=0.2265

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