2. If part of a unit is 5%, or 160, of the unit, what per cent is the remaining part? 3. Draw a line segment 1 dm. long. Mark off 12%; 45%. 4. Draw a line segment of any length. Mark off 25% of it; 15% of it. 5. Express the following per cents as hundredths: 3%; 8%; 25%; 60% 6. Make a drawing to show 10% of 2. Draw a segment 2 decimeters long as shown in the scale drawing below (Fig. 42). Since 10% of a decimeter is equal to 10% of it, show that 10% of 1+1% of 1 = 10% of 2. 7. Exercise 6 shows that 10% of 2 means 10% of 2, or 106 X2. State the meaning of each of the following: 8% of 4; 6% of 8; 3% of 7. 8. Find 5% of 40. 3 x 40 Solution 1: 5% of 40= T6 of 40= 767 X 40= = 2. 100 5 Solution 2: 5% of 40=.05X40=2. 9. Find 5% of 60; 10% of 80; 25% of 200. 20. Uses of per cent in daily life. Measurement by hundredths is used widely in business, in scientific work, and in statistical reports as shown by the following statements: A man saves 10% of his salary. A merchant makes a profit of 20% on his sales. 21. What every pupil should know and be able to do. In the preceding pages the meaning of line segment has been made clear through measuring and drawing. Below is a list of terms and facts which every pupil should understand. 1. The meaning and correct use of the terms: Line, point, segment, unit segment, ratio of two segments, scale drawing, metric system, exact and approximate measure, literal number, ratio of numbers. 2. The meaning of the following principles: a. Through one point any number of straight lines may be drawn. b. Only one straight line can be drawn through two points. c. Two intersecting straight lines can have only one point in common. 3. Understanding of what per cent means. 4. The tables of linear measure in the English and metric systems. 22. Typical problems and exercises. The pupil should be able to use the ruler, squared paper, and compass in measuring and drawing line segments; to add, subtract, multiply, and divide accurately common and decimal fractions; and to write a satisfactory test paper on questions and problems of the type given below. 1. Draw a line segment and find the length using only a ruler; using compass and ruler; using compass and squared paper. 2. Draw a segment and measure it to three figures; to the nearest sixteenth of an inch. 3. Explain the metric sistem of measuring lengths. How are meters changed to centimeters? Centimeters to decimeters? 4. State the meaning of the following symbols: =, >, <. 2.35 3.15 9. Find the grerage of the following measures: 3.64, 3.59, 3.60, 3.01, 3.03, 3.02. 10. The dimensions of a room are 24 ft. by 18 ft. Make a drawing of the room representing 10 ft. by one inch. 210 11. Reduce the ratio to lowest terms. 1:20 12. Write a paper on one of the following topies: a. The need of measurement in daily lite. B. How standard units of measurement have come into use. C Seale drawings d. The metrie system, CHAPTER II HOW WE USE LINE SEGMENTS IN PIC TURING NUMERICAL FACTS REPRESENTING NUMERICAL FACTS BY GRAPHS AND TABLES 23. Picture-representation of numerical facts. Newspapers and magazines often represent numerical statistics, scientific data, or facts by the use of Corn drawings and pictures. Such pictures are known as pictograms, or picture Oats graphs. Thus, the picture graph (Fig. 43) illustrates the amounts of the leading crops in Wheat the United States in 1923, each being pictured by the number of bags on the truck. The differ Barley ences in the crops are easily seen by comparing the various loads as to Rye size. The same facts might be stated in the form of the table on page 36. Fig. 43 REPORT OF THE UNITED STATES DEPARTMENT OF AGRICULTURE FOR 1923 The table should be read as follows: In 1923 the United States raised 3,075,786,000 bushels of corn, etc. In the picture graph (Fig. 44) the height of each figure represents a number of millions. It shows how our continental population kept up a steady rate of increase from one decade to the next. However, in 1920 the population was only 105 millions, while it would have been about 111 millions if it had maintained the rate of increase of the previous decades. |