The probability that a person hits a target is 0.5. What is the probability of at least one hit in 4 shots ?

A box contains 2 white balls, 3 black balls, and 4 red balls. What is the number of ways of drawing 3 balls from the box with at least one black ball?

During war, one ship out of 5 was sunk on an average in making a certain voyage. What is the probability that exactly 3 out of 5 ships would arrive safely?

A card is drawn from a pack of 52 cards. A gambler bets that it is either a spade or an ace. The odds against his winning are