# Junior High School Mathematics Volume 3

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 edition. Excerpt: ...3. 4.5-1. 4. M+3 XX XXX. xx--1 a;--2 a; + 2 13. If a fireman has enough coal to fire one furnace 8 days, or a smaller one 10 days, how long will it last if both are fired? SOLUTION Let x = number of days the coal will last both. Then represents x the part of it that is burned per day. Also the first furnace uses-of it per day, and the second day. Hence the equation per day, and the second---of it. Hence the two use-H of it per 10 8 10. 8 10 x Solve the equation as in exercises 3-12. 14. One boy can mow a lawn in 3 hours and another can mow it in 4 hours. How long at this rate will it take both? 15. It takes one pump twice as long to fill a reservoir as it does another. If the two together can fill it in 4 hours, how long will it take each working alone? 16. A tank is fitted with two pipes, one of which can empty it in 30 min. and the other in 20 min. If the tank is full, how long will it take to empty it if both pipes are left open? 17. A board 12 ft. long is to be cut into two pieces so that the longer length will contain 3 of the shorter length. Find the length of each. CHAPTER VIII INDIRECT MEASUREMENT 1. FINDING HEIGHTS AND DISTANCES: SCALE DRAWINGS You have seen lines used to represent the relative lengths of various objects. In the bar graphs that you have already studied, you saw various magnitudes represented by the length of lines. You are also familiar with the maps of geography and have noticed a "scale " on these maps from which you could measure and compute the distance between any two places. In addition to these, you may have seen shop drawings and blue prints used by engineers and architects. All these maps and plans are "scale drawings" in which real lengths are represented by shorter lines whose relations to...