miles an hour down hill. He walks 56 miles in 20 hours on a road no part of which is level. How much of it is up hill? (Yale.)
3. A physician having 100 cubic centimeters of a 6% solution of a certain medicine wishes to dilute it to a
% solution. How much water must he add? (A 6% solution contains 6% of medicine and 94% of water.) (Case.)
4. A clerk earned $504 in a certain number of months. His salary was increased 25%, and he then earned $450 in two months less time than it had previously taken him to earn $504. What was his original salary per month? (College Entrance Board.)
5. A person who possesses $15,000 employs a part of the money in building a house. He invests one third of the money which remains at 6%, and the other two thirds at 9%, and from these investments he obtains an annual income of $500. What was the cost of the house? (M. I. T.)
6. Two travelers have together 400 pounds of baggage. One pays $1.20 and the other $1.80 for excess above the weight carried free. If all had belonged to one person, he would have had to pay $4.50. How much baggage is allowed to go free? (Yale.)
7. A man who can row
miles an hour in still water rows downstream and returns. The rate of the current is