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 comma circle comma triangle comma line comma 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 80 trials, how many would this person need to get right in order to convince you that ESP may actually exist? Explain.