Brad Doe works for a packaging company. One day, he received four separate orders and accidentally mixed up the addresses, so he applied the address labels at random. What is the probability that exactly three packages were correctly labeled?
Ans: 3/64 = 0.0469 =4.69% First we select 3 packages out of four in 4C3 ways. Probability that these are correctly labelled is 1/4 for each package. And one package must not be correctly labelled for which probability is 3/4. So probability is 4C3 × 1/4 × 1/4 × 1/4 × 3/4 = 3/64
Three points are selected at random on a sphere's surface. What is the probability that they all lie in the same hemisphere? Assume that the great circle, bordering a hemisphere, is part of the hemisphere.
Two cards were drawn, without replacement, from a pack of 52 cards. what is the probability that they are both kings or both queens?
