How did horizontal integration enable rockefeller to monopolize the u. s oil industry?

Alocal club is selling christmas trees and deciding how many to stock for the month of december. if demand is normally distributed with a mean of 100 and standard deviation of 20, trees have no salvage value at the end of the month, trees cost $20, and trees sell for $50 what is the service level?

"in my opinion, we ought to stop making our own drums and accept that outside supplier's offer," said wim niewindt, managing director of antilles refining, n.v., of aruba. "at a price of $21 per drum, we would be paying $4.70 less than it costs us to manufacture the drums in our own plant. since we use 70,000 drums a year, that would be an annual cost savings of $329,000." antilles refining's current cost to manufacture one drum is given below (based on 70,000 drums per year):

When it is 4: 00 a.m. in halifax, it is 1: 00 p.m. in karachi, and when it is 9: 00 a.m. in karachi, it is 5: 00 a.m. in warsaw. mary left halifax to fly to karachi, but she accidentally left her watch on warsaw time. according to mary’s watch, she left halifax at 9: 40 p.m. on monday. the local time when she arrived at karachi was 3: 00 p.m. tuesday. how long was mary’s flight? a. 9 hours, 20 minutes b. 13 hours, 20 minutes c. 14 hours, 20 minutes d. 17 hours, 20 minutes