20. A contractor engages to build a wall 1,540 feet long in 19 days, and hires 30 men. At the end of 11 days he finds only 660 feet of the wall completed. How many additional men must he employ to finish the work in the stipulated time?

Ans. 25 additional men.

21. A certain boiler test showed the following amounts of coal used:

22. An Amoskeag steam fire-engine weighs 7,522 pounds. After water is put in the boiler the weight becomes 8,914 pounds. If water weighs 8 pounds per gallon, how many gallons of water were in the boiler? Ans. 174 gallons.

23. A stone crusher is capable of yielding 27 cubic feet of broken stone per hour. If a cubic foot of stone weighs, on the average, 97 pounds, what weight of stone will be yielded in 4 Ans. 10,476 pounds of stone.

hours?

24. A Corliss engine at the Centennial exhibition made 2,355,300 revolutions. If it made 36 revolutions per minute, how many hours (60 minutes) with how many minutes over an even number of hours did it run? Ans. 1090 hours 25 minutes.

25. To produce a long ton (2,240 pounds) of pig iron the following weights of fuel were consumed:

On this basis what amount of fuel is required to produce a pound

of pig iron?

Ans. 5 lbs.

How

26. A 12-inch gas main delivers 65,936 cubic feet per hour. many feet will it deliver in 14 hours?

Ans. 923,104 cubic feet. 27. A pump delivers 33,720 cubic feet of water in two hours (60 minutes each.) How many cubic feet are delivered per minute? Ans. 281 cubic feet.

28. The weight in detail of a steam hammer is as follows:

What is the total weight in tons (2,000 pounds each)?

Ans. 151 tons.

29. Two internally fired tubular boilers with return flues beneath the shells have each the following heating surfaces:

Heating surface in external shell,

66

66

66

66

66

66

66

173 square feet

115

7

furnaces,
"combustion chamber, 158
"each of 80 tubes,

What is the total heating surface of both boilers?

foot.

Ans. 2,012 square feet.

30. Single belting 36 inches wide costs 7 dollars per running What is the cost of

Double belting costs twice as much.

198 feet of double belting?

Ans. $2,772 cost.

31. What is the total amount of water per hour used by an engine of 213 effective horse-power if it uses 19 pounds per effective horse-power per hour? Ans. 4,047 pounds.

32. If 22 pounds of water per hour per electrical horsepower are used, how many pounds of water per hour are required to furnish 213 horse-power? On the basis of this and the preceding example, how many more pounds are required to furnish 213 electrical horse-power than 213 direct from engine?

Ans.

33. The following bids for paving (with brick) Kansas Ave. (Atchison) from Fourth to Tenth Streets, were received:

34. The heating surface in a locomotive is 88 square feet in the fire box and 792 square feet in the tubes. What is the total heating surface? How many times as much surface is there in the tubes as there is in the fire box?

35. The weight of a car and passengers is as follows:

"75 passengers,

7,000
9,000

66

66

What is the total weight in tons (2,000 pounds)?

Ans. 28 tons.

36. A steam plant has two engines of 934 horse-power each. The starboard engine of a steam ship develops 3218 horse-power and the port engine 3232 horse-power. How much greater power is developed in the ship than in the steam plant.

Ans. 4582 horse-power.

37. The weight of a battery of eight marine boilers and their equipments is as follows:

feet.

38. Each of the above boilers has a grate surface of 95 square
What is the total grate surface of the two batteries?
Ans. 1,520 square feet.

39. A ferry-boat uses 1,560 pounds of coal per hour. The amount of ashes taken from the ash-pit is 171 pounds per hour. What weight of coal goes off through the funnel as gas, etc., in 7 hours? Ans. 9,723 pounds.

40. A dynamo requires 30 horse-power to drive it. It furnishes 18,650 watts. There are 746 watts in a horse-power. How many horse-power does it furnish? Ans. 25 horse-power.

41. If it costs an electric road three cents per passenger for transportation, how many dollars does the road make by carrying 487,600 passengers at 5 cents each (supposing that all of the passengers pay)? Ans. $9,752.

42. The amount of water flowing through a 6-inch turbine is 59 cubic feet per minute. How much water will flow through it in six days (each 24 hours of 60 minutes)?

Ans. 509,760 cubic feet.

43. Assuming the pressure of the atmosphere to be 15 pounds per square inch, what is the atmospheric pressure against a piston 113 square inches in area? What is the total pressure on a square foot, or 144 square inches?

1695 pounds. 2160 pounds.

44. A ship displaces 8,270 tons. Supposing 35 cubic feet of sea water to weigh one ton, how many cubic feet would she displace? Ans. 289,450 cubic feet.

45. At 100 degrees Fahrenheit a cubic foot of water weighs 62 pounds. At 205 degrees a cubic foot weighs 60 pounds. What is the difference in weight between 173 cubic feet of water at 100 degrees and 189 cubic feet at 205 degrees? Ans. 614 pounds.

46. A centrifugal pump delivers 2,371 gallons per minute. A gallon weighs 8 pounds. What weight of water is delivered per minute? Ans. 18,968 pounds.

47. A ship has 360 tons of coal in her steaming 1,360 miles she has consumed 170 tons. has she after steaming 2,320 miles?

After

bunkers.
How many tons

Ans. 70 tons.

48. There are 357 pages in a book. The book is divided into 17 chapters. How many pages are there in a chapter, on the average? Ans. 21 pages.

49. How many kegs of nails, each weighing 100 pounds, are there in three tons (2,000 pounds each)? Ans. 60 kegs.

50. A steamer runs 3,838 miles in 8 days
What is her average speed per hour?

10 hours.
it take her to steam 4,788 miles at the same rate?

(24 hours each),

How long would

51. How many minutes are there in 4 days (24 hours each, and 60 minutes in an hour)? How many seconds (60 in each minute) in the same amount of time?

52. A fly-wheel has a circumference of 30 feet. How far does a point on the edge of it travel in 941 revolutions?

Ans. 28,230 feet.

53. Add 1,743 and 11,469, multiply by 13, divide by 3 and subtract 12,608. Ans. 44,644. 54. A town has 2,549 voters. There are twice as many inhabitants who do not vote. What is the population?

Ans. 7,647 people.

55. How great is the difference between 1,842 divided by 3 and 11,837 divided by 7? Ans. 1,077.

56. How many times is 1,411 contained in 11,288 ? Ans. 8. 57. Multiply 706 by itself and multiply the result by 706. (This is called the cube of 706.) Ans. 351,895,816.

58. Divide 9,807 by 3. Multiply the quotient by 7, subtract 8,493 and add 2,014. Ans. 16,404.

59.

A team is driven 45 miles in 9 hours. A mile is 5,280 feet. If the wheels measure 4 feet on the circumference, i. e., around the tire, how many revolutions do they make in an hour? Ans. 6,600 revolutions.