Question

一道关于边际替代率的问题The absolute value of Mar's MRS at his current c

Answer 1

His preferences frontier is convex. Suppose at one point, MU1/MU2>3, and good1 is at axis X, good2 is at axis Y, now give Mars some of good 1, the point on the frontier moves down. At the new point, MU1/MU2 is smaller, but we don't know if it's bigger than 3 or less than 3. So we are not sure if option D will necessarily make him better off.