A public water utility is trying to decide between two different sizes of pipe for a new water main. A 250-mm line will have an initial cost of $155,000, whereas a 300-mm line will cost $210,000. Since there is more head loss through the 250-mm pipe, the pumping cost is expected to be $3000 more per year than for the 250-mm line. If the lines are expected to last for 30 years, which size should be selected on the basis of a present worth analysis using an interest rate of 10% per year

The social structure in the maya empire was set. it was very difficult to move upwards. status was usually hereditary. occupations for maya men was limited to their father's occupation. if your father was a farmer, you were a farmer. if your father made bricks, you made bricks. there were some exceptions, but they were rare. women, however, could be involved in government, economics, and religion, as well as responsible for hearth, home, and children. still, maya women could not marry outside their social class.