# Question: Let X be the number of defective items found by

Let X be the number of defective items found by a quality inspector in a random batch of 15 items from a particular manufacturing process. The probability distribution of X is provided in the file S04_18.xlsx. This firm earns $500 profit from the sale of each acceptable item in a given batch. In the event that an item is found to be defective, it must be reworked at a cost of $100 before it can be sold, thus reducing its per-unit profit to $400.

a. Find the mean and standard deviation of the profit earned from the sale of all items in a given batch.

b. What is the probability that the profit earned from the sale of all items in a given batch is within two standard deviations of the mean profit level? Is this result consistent with the empirical rules from Chapter 2? Explain.

a. Find the mean and standard deviation of the profit earned from the sale of all items in a given batch.

b. What is the probability that the profit earned from the sale of all items in a given batch is within two standard deviations of the mean profit level? Is this result consistent with the empirical rules from Chapter 2? Explain.

## Answer to relevant Questions

The probability distribution for the number of job applications processed at a small employment agency during a typical week is given in the file S04_43.xlsx. a. Assuming that it takes the agency’s administrative assistant ...An investor puts $10,000 into each of four stocks, labeled A, B, C, and D. The file S04_48.xlsx contains the means and standard deviations of the annual returns of these four stocks. Assuming that the returns of these four ...Suppose that a marketing research firm sends questionnaires to two different companies. Based on historical evidence, the marketing research firm believes that each company, independently of the other, will return the ...Consider two service elevators used in parallel by employees of a three-story hotel building. At any point in time when both elevators are stationary, let X1 and X2 be the floor numbers at which elevators 1 and 2, ...Equation (4.10) for covariance indicates exactly what covariance is: the weighted average of products of deviations from the means, weighted by the joint probabilities. However, the computing formula for covariance, Equation ...Post your question