Introduction to probability：练习题

A fair six-sided die is rolled once. What is the probability of rolling a number greater than 4?

Bag X contains 3 red balls and 2 blue balls. Bag Y contains 2 red balls and 4 blue balls. One ball is selected at random from each bag. What is the probability that both balls selected are red?

A bag contains 5 red balls, 3 blue balls, and 2 green balls. A ball is chosen at random from the bag. What is the probability that the ball chosen is either red or blue?

The probability that it will rain tomorrow is 0.15. What is the probability that it will not rain tomorrow?

A box contains 5 green, 3 yellow, and 2 blue counters. If one counter is picked at random, what is the probability that it is not yellow?

A bag contains only red, blue, and yellow beads. The probability of picking a red bead is 0.3 and the probability of picking a blue bead is 0.45. If one bead is picked at random, what is the probability that it is yellow?

A bag contains 5 green counters, 3 yellow counters, and 2 purple counters. A counter is chosen at random from the bag.
(a) Write down the probability that the counter is yellow.
(b) Find the probability that the counter is not green.