It is known that the standard deviation of the lives of these tubes is 150 150 hours. The company’s research department takes a sample of 100 100 such tubes and finds that the mean life of these tubes is 2250 2250 hours. What is the probability that this sample mean is within 25 25 hours of the mean life of all tubes produced by this company?

Suppose an economist believes that the price level in the economy is directly related to the money supply, or the amount of money circulating in the economy. the economist proposes the following relationship: p=a x m - p=price level - m=money supply - a=a composite of other factors, including real gdp, that change very slowly over time. how might an economist gather empirical data to test the proposed relationship between money and the price level? an economist would persuade the federal reserve to change the money supply to various levels, and observe the resulting changes in the price level. unlike researchers in the hard sciences, economists cannot study complex relationships using data. economists do not usually develop theoretical models of the economy but only analyze summary statistics about the current state of the economy. an economist would look for data on past changes in the money supply, and note the resulting changes in the price level

Arival company manufactures fuel tanks for cars using a different production technique. the total weekly cost (in dollars) of producing x tanks is given by c(x) = 10000 +90x - 0.04x2 find the marginal cost at a production level of 500 fuel tanks per week to approximate the cost of the 501st unit (round to the nearest 2 decimal places, if needed)

Abusiness cycle reflects in economic activity, particularly real gdp. the stages of a business cycle