Question 6.386

41. Price of Crude Oil. The Organization of Petroleum Exporting States reports that the mean price for crude oil in July 2014 was $105.115 (one hundred five dollars, eleven and a half cents) per barrel. Assume the data is normal with mean and standard deviation .

  1. Find the probability that price falls below $100.
  2. What proportion of barrels sell for between $90 and $115?
  3. A low price for oil has a price lower than 99.5% of all other prices. Find the price this represents.
  4. A high price for oil has a price higher than 99.5% of all other prices. Find the price this represents.
  5. Calculate the two symmetric prices for oil and that contain the central 99% of -values between them. Is there a shortcut you can take?

6.5.41

(a) 0.2643 (b) 0.8643 (c) $84.36 (d) $125.64 (e) $84.36 and $125.64; yes, use the answers to (c) and (d)