65. Standard time problems. Since for practical purposes standard time is generally used, the exercises refer to that time unless the contrary is stated. The cities selected are near the time meridians. Cities on the line dividing two time sections usually adopt one or the other.

Questions concerning the date line and the change of day do not involve arithmetic, but belong rather to geography.

ORAL EXERCISE

1. When it is 10 A.M. in Iowa, what time is it in New York? in Wisconsin? in Louisiana? in Ohio?

2. What time is it now in your school? in Boston? in Florida? in Arkansas? in Colorado? in California?

3. When it is 10 A.M. in San Francisco, what time is it in Denver? in St. Louis? in Cleveland? in Albany?

4. When it is 9 A.M. in Denver, what time is it in Los Angeles? in New Orleans? in Cincinnati? in Boston?

5. When it is noon in California, what time is it in Illinois? in Massachusetts?. (Consult the map, page 80.)

6. When it is 3 P.M. in Milwaukee, what time is it in Oregon? in Louisville? in New York? in Philadelphia?

7. When it is 1 P.M. in New York, what time is it in Richmond? in Philadelphia? in Chicago? in California?

8. When it is 9:30 A.M. in New Orleans, what time is it in Alabama? in Maine? in Wyoming? in San Francisco?

9. Suppose a telegram sent from New York at 1 P.M. to San Francisco. If it goes without loss of time, what time will it be when it crosses the Mississippi River? when it crosses Colorado? when it reaches San Francisco?

WRITTEN EXERCISE

1. France uses the time of Paris (2° 20′ 15′′ E.). When it is noon, standard time, in Iowa, what is the time in France?

2. Japan uses the time of 135° E. When it is noon at Greenwich, what is the time in Tokyo? in St. Louis? in Portland, Oregon?

3. All of Great Britain uses Greenwich time. If it is 5: :30 P.M. at Liverpool, what is the local time of a ship in 17° 16' 30" W. longitude?

4. The longitude of Chicago is 87° 36' 42" W. What is the difference between the local (that is, the real meridian) and standard time?

5. Italy uses the Central European time (15° E.). When it is 7:30 A.M. in Springfield, Illinois, what time is it in Rome (7 hr. later)? in London?

6. When it is 1 P.M. in London, what is the time in Paris? (See Exs. 1, 3.)

7. The longitude of San Francisco is 122° 25' 40.8" W. Which is the later, local or standard time, and how much?

8. Berlin uses the standard time of 15° E. The longitude of Berlin is 13° 23′ 43.5". What is the difference between the local and standard time?

9. What is the difference in standard and in local time between Berlin and San Francisco? (See Exs. 7, 8.)

10. At midnight, December 31, 75° time, the United States Naval Observatory sends an electric time signal to various parts of the world, indicating that a new year is beginning at Washington. When does the signal reach California? Colorado? Alabama? England? Germany?

1. What is the difference between the local and standard time of New York? of Albany?

2. What is the difference in local time between Berlin and Paris? Berlin and New York?

3. What is the difference in local time between Albany and San Francisco? Albany and Paris?

4. What is the difference in local time between New York and Chicago? Chicago and San Francisco?

5. When it is 1 P.M., standard time, at Chicago, what is the standard time at San Francisco? the local time?

6. When it is noon, local time, at Albany, what is the standard time there? What is then the standard time at Chicago?

What differences of local time correspond to these differences of longitude?

1. F is what part as large as E? what per cent? 2. F is what part as large as D? what per cent? 3. F is what part as large as C? what per cent?

4. F is what part as large as B? 5. F is what part as large as A?

Tell what per cent

what per cent?

what

per cent?

16. C is of E.

17. D is of E.

15. A is of D. 18. Find 10%, or 1, of 50, 175, 212, $327, $475.50. 19. Find 50%, or, of 86.4, $16.44, $244.50, $862.20. 20. Find 12%, or, of 16, 80, 96, 728, 488, 648, $840. 21. Find 16%, or, of 36, 66, 90, 720, 366, 540, $636. 22. Find 20%, or , of 75, 90, 250, 305, 555, 750, $3.50. 23. Find 25%, or 4, of 64, 96, 324, 4.40, 2.40, 320, $840. 24. Find 33%, or, of 63, 96, 3.33, 1.50, 630, 900, 324.

Sam is 6 years old, Nora is 9, and Tom is 12. Tell the following per cents:

25. Sam's age is what per cent of Tom's?
26. Sam's age is what per cent of Nora's?
27. Nora is what per cent older than Sam?
28. Sam is what per cent younger than Nora?

29. Nora's age is what per cent of Tom's? of Sam's? 30. Tom is what per cent older than Sam? than Nora? 31. Nora's age is what per cent of the sum of Sam's and Tom's?

32. Nora's age is what per cent of the product of Sam's and Tom's?

33. Sam's age is what per cent of the difference between Nora's and Tom's?

It is 3000 miles from London to New York, 1000 miles from New York to Chicago, and 2000 miles from Chicago to San Francisco. Tell the following per cents:

34. The distance from Chicago to San Francisco is what per cent of that from London to Chicago?

35. The distance from New York to Chicago is what per cent of that from London to San Francisco?

36. The distance from New York to Chicago has what ratio to that from Chicago to San Francisco?

37. The distance from New York to San Francisco has what ratio to that from London to San Francisco?

38. The distance from London to New York is what per cent greater than that from New York to Chicago?

39. The distance from London to New York is what per cent less than that from London to San Francisco?