Question

This is a MML exercise of of Sullivan's Essential Statistics. I don't know why this is true. See attached high lighted question.

Answer 1

See attached

Answer 2

If we can exclude (or correct for) loss of height at older ages due to loss of skeletal mass, then we could say that men born 80 years ago were (on average) shorter than men born 60 years ago, who were shorter than men born 40 years ago, ... In other words, men were shorter years ago, and are taller now...