Charpentier’s three deck illusion

A participant is asked to lift all three decks and then the top deck alone. The participant will think the top box weighs more than all three boxes combines. How does this work? Charpentier, a French physician, discovered this illusion over 100 years ago. The illusion occurs when a person underestimates the weight of a larger object (Three decks) when compared to a smaller object of the same mass (Top deck).
The top deck is filled with 84 pennies and the bottom 2 decks are h