2) amy is training for a competition, a timed race that combines swimming, rowing, and running. consider the following statement: because her pool sessions are her swim more quickly, amy plans to reduce by 30 minutes per week the time she spends training on rowing and increase by 30 minutes the time she spends in the swimming pool; however, her bff says that she should stop doing any rowing and running and spend all 15 hours per week training in the pool. which concept does amy’s plan demonstrate that her bff's advice does not? people generally take advantage of opportunities for self-gain many decisions are made on the margin. markets are usually efficient everything has a cost