Ask Marilyn In a September 19, 2010, article in Parade Magazine written to Ask Marilyn, Marilyn vos Savant was asked the following: Four identical sealed envelopes are on a table, one of which contains $100. You are to select one of the envelopes. Then the game host discards two of the remaining three envelopes and informs you that they do not contain the $100. In addition, the host offers you the opportunity to switch envelopes. What should you do? (a) Keep your envelope; (b) switch; (c) it does not matter.

Write a simulation to find the probability in R studio of selecting the $100 bill when you switch. Confirm the results of your simulation with an exact analysis.