38. One team in a baseball league has won 14 games out of 20 played. What is the team's rate of winning per hundred games? 39. In a certain class 9 out of every 10 pupils were present. The whole class numbered 70. How many were present? SOLUTION. Let n = number of pupils present. Ans. 63 pupils were present. 40. At 45 cents a dozen how much will 16 oranges cost? (The ratio of 16 to 12 ratio of what number to 45?) Form the equation and solve it. = 41. Bananas are selling 15 for 25 cents. How much are they per dozen? (Be sure to arrange your statement so that the required number is the first number of one ratio.) 42. Lemons are selling 3 for 5 cents. How much will 11⁄2 dozen cost? 43. Tumblers are selling at 40 cents a dozen. How much will 9 tumblers cost? 44. If 4 apples cost 5 cents, what will 10 apples cost? 45. If soap is selling at 6 bars for a quarter, how much will 4 bars cost? 46. Post cards are sold at 80 for $1.00.. How much will 25 cost? 47. American League baseballs are sold at $15.00 a dozen. Find the cost of 5 balls. 48. If 25 yards of cloth cost $7.50, how many yards can be bought for $69? 49. A school contains 2025 pupils; 4 out of every 9 are foreign born. How many pupils are foreign born? 50. If an aëroplane flies 65 miles in 24 hours, how far will it fly in 4 hours? 51. On a certain map a line 14" long represents a distance of 120 miles. What distance is represented by a line 5" long? 52. At $7.75 a hundred pounds, find the cost of 275 pounds of lamb. 53. If 50 feet of garden hose sell at $5.75, what will 125 feet cost? 54. At $7.50 a ton of 2000 lb., what will 7000 lb. of coal cost? 55. The ratio is what rate per hundred? CHAPTER III MEASUREMENT I. LINES AND ANGLES 28. Lines and Planes. Many of the surfaces about you are flat; for example, the blackboards, the top of your desk, the floor, the walls. These surfaces are called plane surfaces or planes. If you draw a line on one of these surfaces with the aid of your ruler you say the line is straight, which means that it has the same direction, however long you make it. TABLE OF LINEAR MEASURE [For the work that follows the pupil should have a ruler graduated in sixteenths of an inch on one edge and tenths of an inch on another.] 1. To test the straightness of the edge of your ruler, mark two points on a piece of paper. Using your ruler draw a line through them. Turn the ruler over and draw a line through the same two points along the same edge. If the ruler has a straight edge, would the two lines be different lines or the same line? [For this and other constructions your pencil should be sharpened to a fine point.] 46 2. How many points are necessary to show the direction of a straight line? 3. How may a straight-edged ruler be used to test whether a surface is plane or not? [Place the edge of your ruler against the surface to be tested. If the edge touches the surface at all points for every possible position of the ruler, the surface is plane.] Test the top of your desk, the blackboards, and other objects that you think are plane. 4. Draw a straight line § of an inch long. Compare it with a line .6 of an inch long. With a line .7 of an inch long. 5. Draw a straight line with a line 1.8 inches long. 6. Draw four straight Measure each to the nearest tenth of an inch. Add the lengths and divide the sum by 4 to get the average length of the four lines. 17 inches long. Compare it With a line 1.9 inches long. lines of different lengths. 7. Draw five straight lines of different lengths. Measure each to the nearest tenth of an inch. Find the average length of the five lines by adding them and dividing by 5. 8. Draw three straight lines and measure as above. Find the average length. 9. Measure the two A straight lines in Fig. 2 to the nearest tenth of C・ an inch. Find the ratio FIG. 2 B -D of the two lines. Their lengths are 1.2 in., and 1.8 in., |