sible to derive additional facts that are not actually stated in the table or drawn in the diagram. For example, in Fig. 54, we may estimate the population in 1895, or in 1855; we may even predict what under ordinary conditions should be the population in 1930. Changing prices of a commodity, temperatures, stock fluctuations, cost relations, are best pictured by line graphs. EXERCISES 1. The graph (Fig. 55) shows the hourly variation of telephone calls in a great city. Study the graph and answer the following FIG. 55. ONE DAY OF NEW YORK'S TELEPHONE TRAFFIC. questions. When do people use the telephone most often? How do the calls between nine and ten compare with the calls between eight and nine? How do you account for the drop between twelve and two? 2. The graph (Fig. 56) gives the changes in the price of wheat for one year. What was the price on the first day of each month? When was it lowest? When was it highest? What is your explana Jan. Feb Mar Apr May Jun July Aug. Sept. Oct." Nov. Dec. tion of the last two answers? In which month was the advance greatest? When was the drop greatest? When was the price 65¢? 3. Study the graph (Fig. 57). Find out why immigration was low in 1862, 1896 and high in 1883, 1907. How do you explain the FIG. 57. THE RISE AND FALL OF IMMIGRATION. 4. Make a graph of imports of raw cotton from the United States to Great Britain for 1918 to 1922: 9,760,182; 13,707,407; 13,950,461; 8,019,925; 9,146,237. 5. The average monthly rainfall or melted snowfall for a certain city is given in the table below. Make a line graph representing this table letting 2 cm. denote 1 inch. Follow the directions given on page 40. Months Inches. Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 2.8 2.30 2.56 2.70 3.59 3.79 2.61 2.83 2.91 2.63 2.66 2.71 6. The hourly temperatures on a certain day were as follows: Time of day.. 6:00 a.m. 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 Temperatures. 48° 49° 53° 55° 61° 65° 70° 72° 72° 70° 65° 63° Make a line graph of this table and tell what the graph shows. Find the average temperature. 7. Make a bar graph of the number of points made by pupils in a written test recorded below. 8. The average length of day from sunrise to sunset varies (changes) with the latitude. Represent by a line graph the following average lengths of days in latitude 45°, letting 1 cm. represent one hour. Months. Hours Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 9.1 10.4 11.9 13.5 14.9 15.6 15.3 14.1 12.6 11.1 9.6 8.8 9. Represent by a bar graph the fire losses in the city of Chicago given in the following table: Years. Number of millions of dollars lost.. 1912 1913 1914 1915 1916 1917 1918 914 1915 19. 6.655.016.01 4.9 5.494.184.08 10. The table below gives the death rates caused by influenza and pneumonia in some of the large cities during the epidemic in 1918. Compute the increase in the death rate from 1917 to 1918. Make a bar graph of the increases and tell what the graph shows. Death RATES CAUSED BY INFLUENZA AND PNEUMONIA 11. Select the most convenient unit and then make a bar graph representing the facts in the table below, which gives the production of corn in several states. Suggestion: Use only the first three figures for making the graph. PRODUCTION OF CORN IN SEVERAL STATES Compare by means of your graph, and by means of ratio, the productions of the following states: Iowa with Missouri; Iowa with Indiana; Missouri with Kentucky; each state with Illinois. 12. Make graphs representing the heights of the following buildings in New York City: Woolworth 750 feet, Metropolitan 700 feet, Singer 612 feet, Equitable 486 feet, Times 420 feet, Flatiron 286 feet. Represent by a bar the tallest building in your city. Find the ratio of each of the buildings above to the height of your tallest building. 13. The height of the average man is about 5 ft. 5 inches. The average weight for men 5 ft. tall is given in the following table for different ages. Make the graph. Ages. Pounds. 15-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 134 138 141 143 146 147 149 149 148 147 14. Represent graphically the average weights of boys and girls given in the following table: 15. The table below gives a record of a typical day's demand for electricity in New York. Make a graph of this table and explain the following facts shown in the graph: very little demand at 4 A.M.; the rapid increase from 5 to 7 A.M., and from 7 to 9 A.M.; the great demand at 11 A.M.; the sudden drop at 12:30; the largest demand at 5 P.M.; the slow decrease from 7 to 9 as compared with that from 5 to 7 and from 9 to 12 P.M. 1000 kilowatts.. 135 158 187 180 180 233 198 159 154 135 118 90 |