Middle School:
Question: Lisa needs to memorize the locations of all 54 countries in Africa for a geography test that will be 30 days from now. She memorizes 7 countries every 3 days. Every 2 days, she forgets a country and needs to rememorize it. Will she have enough time to memorize all of the countries in Africa for her geography test?
Answer: Yes
Solution: Since there are 10 3-day periods in 30 days, Lisa can memorize the location of a country a total of 7 × 10 = 70 times. That means she has time to forget and relearn 70 – 54 = 16 of them. If she forgets 1 every 2 days, that means she forgets 30 ÷ 2 = 15 of them, and since 15 is less than 16, she will have time to re-memorize them all.
Mathnasium of West Covina is a math-only learning center for K-12 students in West Covina, CA. Trusted by over a million parents, Mathnasium uses personalized learning plans and the proprietary Mathnasium Method™ to help students catch up, keep up, and get ahead on their math journey.
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