15. What is the value of a lot 70 rd. long and 20 rd. wide, at $47.25 per acre?

16. A cistern has 3 pipes. The first will fill it in 12 hours, the second in 16, and the third in 18 hours. If all run together, in what time will they fill it? (State this example as a proportion, if you can.)

17. What is the difference between the simple interest on $328 for 2 y. 7 mo. at 7%, and the compound interest on the same sum for the same time at 6% ?

18. Find the balance due March 4, 1881, on a note dated Jan. 1, 1879, for $ 580, at 5%, on which a payment of $ 85 has been made every 6 months, using the United States rule.

19. How much should be discounted on a bill of $3725.87, due in 8 mo. 10 d., if paid immediately, money being worth 5%?

20. Bought bonds at 115, and sold at 110, losing $300. How many bonds of $1000 each did I buy?

21. If A puts in $4000 capital for 8 months, B $ 6000 for 7 months, and C $3500 for 1 year, and they gain $ 2320, what is each partner's share of the gain?

22. If 5 horses eat as much as 6 oxen, and 8 horses and 12 oxen eat 12 tons of hay in 40 days, how much hay will 7 horses and 15 oxen eat in 65 days?

23. Find the value of 0.000238328.

24. A steamer goes due north at the rate of 15 miles an hour, and another due west 18 miles an hour. How far apart will they be in 6 hours?

25. Find the cost, at 30 cents per sq. yd., of cementing the bottom and sides of a cubical cistern that will hold 300 barrels. 26. What is the area of a circle 5 ft. in diameter ?

27. What is the difference between 5 square feet and 5 feet square? Illustrate by a diagram.