minutes. How many miles per hour was that? Compare his rate of travel with that of a fast passenger train.

19. On Feb. 6, 1919, the pilot mentioned in problem 18 flew from Cleveland, O., to Washington, D.C., in a nonstop flight in 2 hours 58 minutes, distance 450 miles. Compare the average speed on this trip with that in problem 18.

20. On Feb. 21, 1919, Col. Walter G. Kilner flew in a DeHaviland machine from Riverside, Cal., to Rockwell Field, distance 115 miles, in 38 minutes. What was the average speed per hour?

21. In June, 1919, Capt. John Alcock and Lieut. Arthur Brown, two British officers, made the first non-stop transAtlantic flight. They flew from Newfoundland to Clifden, Ireland, in 16 hr. 12 min., distance 1960 mi. Compute their average hourly rate of travel.

HINT.-Think 16 hr. 12 min. as 16.2 hr.

22. Lieutenant Belvin Maynard drove an airplane in Oct. 1919, from Mineola, Long Island, to San Francisco, Cal., distance 2700 miles, in 24 hr. 59 min. 48 sec. His closest competitor, Major Carl Spatz, made the same trip in 26 hr. 13 min. 14 sec.

(1) How much did Maynard lack of requiring 25 hours for his trip?

(2) How much did he beat Major Spatz?

(3) Compute the average speed per hour of each, calling the time of one 25 hours and that of the other 26 hr. 13 min.

Route of the First Transcontinental Air Mail, August 21, 1923 23. On Aug. 21, 1923, Pilot Johnson carrying the first transcontinental air mail westward left New York City at 11.01 A. M., Eastern Time, and landed at Cleveland, Ohio, at 4.14 P. M., Eastern Time. What was the average rate of flight per hour?

24. Pilot Smith left Cleveland at 4.18 P.M., Eastern Time, and arrived in Chicago at 6.50 P.M., Central Time. What was his average speed per hour?

HINT.—The actual time elapsed between the two stations was 3 hr. 32 min.

Why?

25. On Aug. 21, 1923, Pilot Winslow carrying the first transcontinental air mail eastward left San Francisco at 5.59 A.M., Pacific Time, and arrived in Reno, Nev., at 7.46 A.M., Pacific Time.

(1) Compare Winslow's average speed with that of Johnson in problem 23.

(2) Compare Smith's average speed in problem 24 with that of Winslow.

26. The air mail for the east left Reno at 7.50 A.M.,

Pacific Time, and arrived in Salt Lake City at 1.18 P.M., Mountain Time. What was the average speed?

27. The transcontinental air mail left New York City Aug. 23 at 10.57 A.M. on its third westward trip and arrived at San Francisco Aug. 24 at 1.34 P.M.

(1) What was the actual time required for the trip? (2) Find the average rate of speed.

(3) The six stops enroute required a total of 60 min. Compute the average speed based on the actual flying time.

28. The air mail on its third eastward trip left San Francisco Aug. 24 at 6 A.M. and arrived at New York City Aug. 25 at 11.14 A.M.

(1) Compare the actual time enroute with that of the corresponding westward trip. See problem 27.

(2) Compare the average speed and also the average speed based on actual flying time, which is 60 min. less than the time enroute, with those of the corresponding western trip. See problem 27.

29. In each of the four eastbound trips the actual flying time was from 1 hr. to 3 hr. shorter than that of the corresponding western trip. How do you account for this difference in speed?

30. In 1920 a plane was flown on Long Island at the rate of 156.5 mi. per hr. At Omaha in 1920 the highest rate of speed attained was 176.7 mi. per hour. At Detroit in 1922 the maximum speed was 205.8 mi. per hour. At St. Louis in 1923 a speed of 243.67 mi. per hour for the entire course of 124.88 mi. was reached.

Construct a line graph to represent these facts.

CHAPTER XII

ECONOMY AND THRIFT

This chapter contains problems intended to show how a knowledge of arithmetic enables one to practice economy and thrift, by helping to answer the question, "Will it pay?” or “Did it pay?" or "Which course of action is most economical?"

Thrift in the School

1. The children of the Mullanphy School collected in two months 11325 lb. of old newspapers and 2550 lb. of magazines. They received $1.25 per 100 lb. for the newspapers and $2.75 per 100 lb. for the magazines. What was the total received for old paper?

2. The children of the school named in the previous problem collected from Sept. 1, 1919, to Jan. 1, 1920, 17975 lb. of old magazines. What was the average amount received per month at the price named in the previous problem?

3. The children of the public schools of St. Louis during March and April, 1920, collected, weighed, and computed the value of 267450 lb. of old newspapers and 28514 lb. of old magazines. Newspapers were priced at $1.25 per 100 lb.; magazines at $2.75 per 100 lb. Find the total value.

4. If the children had not collected this old paper, what would probably have happened to most of it? Name several ways in which collecting and selling old paper promotes thrift?

Each of the above amounts equals 1 qt. of milk in energy

1. If you use the cost of a quart of milk as the basis, which is the cheaper food at the prices stated in the table; oranges or bananas? eggs or sirloin steak? English walnuts or fish? eggs or fish?

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2. Which is the most expensive food? Which is the cheapest at the prices quoted?

3. Calling the energy* value of 1 qt. of milk one, or 100%, find the % of energy value in 1 lb. of each of the other foods in the figure.

*Energy is ability to do work.