18. Calves, in dressing, lose about 40% of their weight; what was the live weight of a calf whose dressed weight is 80 lb. ?

19. When 10 lb. of green tea are mixed with 15 lb. of black tea, what per cent of the mixture is black tea and what per cent is green tea?

20. In a crate of eggs containing 6 doz., 9 eggs were found broken; what was the loss per cent from breakage?

21. All school buildings hereafter built or rebuilt in Pennsylvania must have the total light area equal to at least 20% of the floor space. What is the least light area a school building may have whose floor space is 1200 sq. ft.?

22. If 37% of the pupils in a school are boys and there are 40 girls in this school, how many pupils are there?

23. The standard gold coin of the United States is 9 parts pure gold and 1 part alloy. What per cent is alloy ? What per cent is pure gold?

24. Pure gold is designated as 24 carats fine; what is the per cent of gold in jewelry that is 18 carats fine?

25. A man bought a horse for $275 and sold it for 20% more than he paid for it; what was the selling price?

26. 10% of all U. S. silver coin is copper alloy; find the weight of the copper and also of the silver in a silver dollar, the weight of which is 412.5 gr.

27. How much does a merchant lose of a bill of $275, if he is able to collect only 75% of it?

28. Water expands 10% of its volume in freezing; how many cubic feet of ice can be made from 100 cubic feet of water?

of potash, 1.5% of how many pounds.

29. Wood ashes contain about 5% phosphoric acid, and 32.5% of lime; of each of these substances are in a ton of wood ashes ?

30. If a miller takes 10% of each bushel of corn ground for toll, and there is also a loss of about 1% in grinding, how many pounds of feed should be returned to a farmer for 30 bu. (56 lb.) of corn?

31. Potatoes are about 75% water, and of the remainder about 64.8% is starch; how many pounds of starch are there in 200 lb. of potatoes?

32. After a piece of cloth had shrunk 5% of its length, it measured 38 yd.; how many yards did it measure before shrinking?

33. After a laborer's wages had been increased 20%, they were $54 a month; what were they before the increase?

34. A merchant's sales for a certain day were $714.35, which was 87% of his sales the preceding day. What were his sales for both days?

35. Corn is about 5.4% fat; how many pounds of fat

are there in 20 bu. (56 lb.) of corn?

36. A horse was sold for 12% less than it cost. was sold for $175, what was the cost?

If it

37. Last year a farmer's wheat crop yielded 20 bu. to the acre. This year it yielded 21 bu. to the acre. What was the per cent of increase?

38. If a teacher's salary is advanced from $60 to $65 per month, what is the per cent of increase?

39. If 1 cu. ft. of cement be mixed with 2 cu. ft. of sand and 4 cu. ft. of broken stone to make concrete, what per cent of the mixture is cement? What per cent of the mixture is sand? What per cent of the mixture is broken stone?

40. In the 8th grade of the schools of a certain city 210 minutes are assigned per week to the subject of arithmetic. If the school is in session 1500 minutes per week, what per cent of the total time is assigned to arithmetic?

41. When tomatoes are advanced in price from 10 to 12¢ per can, what is the per cent of advance?

42. What is 7% of $600?

SUGGESTION. Move the decimal point two places to the left, and multiply the result by 7.

43. The amount of land surface in New Jersey is 7455 sq. mi., and the amount of water surface 360 sq. mi.; what per cent of the area of the state is land and what per cent water? Answer correct to the nearest .01%.

44. On an investment of $85.38 a man gained $4.75; find the rate per cent of gain, correct to the nearest .01 %.

45. In ten years, recently, the population of Oklahoma increased from 398,331 to 1,637,155; find the per cent of the increase, correct to the nearest .01%.

46. In ten years, recently, the population of Indianapolis increased from 169,164 to 233,650. Find the per

cent of increase, correct to the nearest .1%.

47. In ten years, recently, the population of Lansing, Mich., increased from 16,485 to 31,489. What was the per cent of increase, correct to the nearest .1% ?

48. During ten years, recently, the population of a certain township decreased from 875 to 854.

What was

the per cent of decrease, correct to the nearest .1% ?

49. A long ton is how many per cent more than a short ton?

50. A man's investment earned him, during a certain year, $135. This was 4.5% of the investment; what

was the investment?

COMMERCIAL DISCOUNT

209. Commercial Discount is any deduction made from the list price, the time price, or the marked price of goods; the net price is the remainder.

210. If but one discount is made on any price, a certain per cent of that price is deducted; if two or more discounts are made, the first discount is reckoned on the price, the second on the remainder, the third on the next remainder, and so on.

Thus, if an article is marked $ 0.80 and sold at a discount of 25 %, the discount is 25% of $0.80, or $0.20. If it is sold at a discount of 25% and 10%, the second discount is 10 % of $ 0.60, or $0.06, and the total discount is $ 0.26.

Illustrative Example

What is the net cost of a bill of goods listed at $240 and bought at 20% and 12% off?

Explanation:

20 %, or, of $ 240, or $ 48

$240 - $48, or $192

=

the first discount. = the first remainder.

12%, or, of $192, or $ 24 = the second discount.

211. Business men generally convert two successive rates of discount into an equivalent single rate before they reckon the discount; to do so they use the following:

A single rate of discount equivalent to two successive rates equals their sum diminished by 10 of their product.

Thus, a single rate of discount equivalent to

State at sight the missing discounts in Examples 1-10: