One rather dismal afternoon with very little to do, you decide to play a game with your roommate,

Celia. Celia rolls a die, and you ip a coin the number of times showing on the die. Your other roommate,

Ruth is in the kitchen studying for her math exam. When she comes out you tell her the exciting new

that you have ipped a total of 3 heads. Ruth tells you the most likely number that was on Celia's die.

Explain Ruth's answer.