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If the standard deviation of the lifetimes of vacuum cleaners is estimated to be 300 hours, what sample size must be selected in order to be 97% confident that the margin of error will not exceed 40 hours?

Through a telephone survey, a low-interest bank credit card is offered to 400 households. The responses are as follows:​Income ≤ $50,000Income > $50,000Accept offer4030Reject offer210120​a. Develop a joint probability table and show the marginal probabilities.b. What is the probability of a household whose income exceeds $50,000 and who rejects the offer?c. If income is ≤ $50,000, what is the probability the offer will be accepted?d. If the offer is accepted, what is the probability that income exceeds $50,000?​​​​​

A company has recorded data on the daily demand for its product (y in thousands of units) and the unit price (x in hundreds of dollars). A sample of 11 days’ demand and associated price resulted in the following data: ∑ x = 154∑ x 2 = 2,586∑ y = 451∑ y 2 = 18,901∑ xy = 5,930​a.Using the above information, develop the least-squares estimated regression line.b.Would the demand ever reach zero? If yes, at what price would the demand be zero? Show your complete work.​

In a random sample of 500 college students, 23% say that they read or watch the news every day. Develop a 90% confidence interval for the population proportion. Interpret your results.

A couple has three children. Assuming each child has an equal chance of being a boy or a girl, what is the probability that they have at least one girl?

Excel’s POISSON.DIST function can be used to compute _____.

Through a telephone survey, a low-interest bank credit card is offered to 400 households. The responses are as follows:​Income ≤ $50,000Income > $50,000Accept offer4030Reject offer210120​a. Develop a joint probability table and show the marginal probabilities.b. What is the probability of a household whose income exceeds $50,000 and who rejects the offer?c. If income is ≤ $50,000, what is the probability the offer will be accepted?d. If the offer is accepted, what is the probability that income exceeds $50,000?​​​​​

An investment advisor recommends the purchase of shares in Infogenics, Inc. He has made the following predictions:P(stock goes up 20% | rise in GDP) = 0.6P(stock goes up 20% | level GDP) = 0.5P(stock goes up 20% | fall in GDP) = 0.4An economist has predicted that the probability of a rise in the GDP is 30%, whereas the probability of a fall in the GDP is 40%.a. Draw a tree diagram to represent this multiple-step experiment.b. What is the probability that the stock will go up 20%?c. We have been informed that the stock has gone up 20%. What is the probability of a rise or fall in the GDP?

The Harbour Island Ferry leaves on the hour and at 15-minute intervals. The time, x, it takes John to drive from his house to the ferry has a uniform distribution with x between 10 and 20 minutes. One morning John leaves his house at precisely 8:00 A.M.a. What is the probability John will wait less than 5 minutes for the ferry?b. What is the probability John will wait less than 10 minutes for the ferry?c. What is the probability John will wait less than 15 minutes for the ferry?d. What is the probability John will not have to wait for the ferry?e. Suppose John leaves at 8:05 A.M. What is the probability John will wait (1) less than 5 minutes for the ferry; (2) less than 10 minutes for the ferry?f. Suppose John leaves at 8:10 A.M. What is the probability John will wait (1) less than 5 minutes for the ferry; (2) less than 10 minutes for the ferry?g. What appears to be the best time for John to leave home if he wishes to maximize the probability of waiting less than 10 minutes for the ferry?

In a laboratory, what does ‘universal precautions’ refer to?