Direct Variation and Proportion (For use with Lesson 8-1) By working through the steps in the problems below, you will gain skill in solving problems involving direct variation. Problem I The average gain in the masses of rats fed an experimental diet was directly proportional to the n of weeks that the experiment was run. If the average mass gained after 5 weeks was 71 g. find th erage gain in mass after 3 weeks. a. What ratio must be constant? Give your answer in words. b. Let g = the gain in mass in grams and w = the number of weeks Write an algebraic equation that includes constant of proportionality. c. Write an algebraic equation in the form of a proportion. d. Use your equation from part (b) or your equation from part (c) to write an cquation with exactly one unknow e. Solve your equation and answer the question. f. Check to see if the two values of the ratio identified in part (a) are equal