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Summer 2012 Understanding Ratios 1. The ratio of the number of boys to the number of girls at Archimedes’ Junior High School is 4:5. a) What fraction of the students are boys? b) If there are 140 boys, how many students are there altogether? Solve this problem in at least 2 ways. 2. A grocery store sells rice in bulk. The sign says: $4 for 5 pounds. At this store, you can buy any number of pounds of rice at a time, and all prices include tax. Alberto said, “The ratio of the number of dollars to the number of pounds is 4:5. That’s $.80 per pound.” Beth said, “The sign says the ratio of the number of pounds to the number of dollars is 5:4. That’s 1.25 pounds per dollar.” a) Are Alberto and Beth both correct? Discuss with your group members. Understanding Ratios Page 1 of 2 Adopted by Illustrative Mathematics – Content Standards: Kindergarten Through Grade 8 (Grade 6), www.illustrativemathematics.org Summer 2012 b) Claude needs 2 pounds of rice. Show Claude how much money he will need. Solve this problem in at least 2 ways. c) Dora has $10 and wants to stock up on rice. Show Dora how many pounds of rice she can buy. Solve this problem in at least 2 ways. d) Do you prefer to answer parts (b) and (c) using Alberto’s rate of $.80 per pound, using Beth’s rate of 1.25 pounds per dollar, or using another strategy? Discuss with your group members. 3. Compare problems 1 and 2 above and note any similarities or differences. Discuss with your group members. Understanding Ratios Page 2 of 2 Adopted by Illustrative Mathematics – Content Standards: Kindergarten Through Grade 8 (Grade 6), www.illustrativemathematics.org