There are two types of mixture problems: TYPE 1. This type of mixture problem deals with solutions or alloys containing different percentages of the ingredients. Relationships should be expressed between amounts rather than between percents. Thus, 20 gallons of a 60% solution of acid contain an amount of acid equal to 60% or 3/5 of the solution: 3 20 x - = 12 gallons of acid. 5 :RA NOTE: an alloy consists of copper and tin in the ratio of 9:2 by weight. If a casting made of this alloy weighs 55 pounds, how many pounds of tin does it contain? 9x + 2x = 55 11x = 55 x = 5 Tin is 2x = 10 lbs. Ans. :RA TYPE 2. This type involves blending of materials having different unit values. For example, we may mix coins of different denominations; coffees whose per-pound values differ; monies whose interest rates are not the same; tickets sold at different prices; and so forth. The same treatment applies to all: the total value of one ingredient plus the total value of the other must equal the total value of the blend or mixture. Be careful, however, to use the same units throughout. :ET :ET Copyright ARROW INSTRUCTIONAL SYSTEMS July 1983
