# Question: A college bookseller makes calls at the offices of professors

A college bookseller makes calls at the offices of professors and forms the impression that professors are more likely to be away from their offices on Friday than any other working day. A review of the records of calls, 1/5 of which are on Fridays, indicates that for 16% of Friday calls, the professor is away from the office, while this occurs for only 12% of calls on every other working day. Define the random variables as follows:

a. Find the joint probability distribution of X and Y.

b. Find the conditional probability distribution of Y, given X = 0.

c. Find the marginal probability distributions of X and Y.

d. Find and interpret the covariance between X and Y.

a. Find the joint probability distribution of X and Y.

b. Find the conditional probability distribution of Y, given X = 0.

c. Find the marginal probability distributions of X and Y.

d. Find and interpret the covariance between X and Y.

## Answer to relevant Questions

A restaurant manager receives occasional complaints about the quality of both the food and the service. The marginal probability distributions for the number of weekly complaints in each category are shown in the ...A car salesperson estimates the following probabilities for the number of cars that she will sell in the next week: a. Find the expected number of cars that will be sold in the week. b. Find the standard deviation of the ...It is estimated that 55% of the freshmen entering a particular college will graduate from that college in four years. a. For a random sample of 5 entering freshmen, what is the probability that exactly 3 will graduate in ...Shirley Johnson is developing a new mutual fund portfolio and in the process has asked you to develop the mean and variance for the stock price that consists of 10 shares of stocks from each of the following firms: Alcoa ...A contractor submits a bid on a project for which more research and development work needs to be done. It is estimated that the total cost of satisfying the project specifications will be $20 million plus the cost of the ...Post your question