You decide to test a friend for ESP using a standard deck of 52 playing cards. Such a deck contains 13 spades, 13 hearts, 13 diamonds, and 13 clubs. You shuffle the deck, select a card at random, and ask your friend to tell you whether the card is a spade, heart, diamond, or club. After the guess you return the card to the deck, shuffle the cards, and repeat the above. You do this a total of 100 times. Let X be the number of correct guesses by your friend in the 100 trials. What is the probability that X ? 30 if your friend is just guessing? Use the normal approximation with the continuity correction