ESP
Scientists wish to test the mind-reading ability of a person who claims to have ESP. They use five cards with different and distinctive symbols (square, circle, triangle, line, squiggle). Someone picks a card at random and thinks about the symbol. The mind reader must correctly identify which symbol was on the card.
If the test consists of 100 trials, how many would this person need to get right in order to convince you that ESP may actually exist? Explain.