Probability: แบบฝึกหัด

A bag contains 20 identical cards, numbered from 1 to 20. A card is randomly drawn from the bag. What is the probability that the number on the card is an odd prime number?

A number is chosen at random from the set of integers from 10 to 30 inclusive. What is the probability that the chosen number is a multiple of 4 or a multiple of 6?

A fair six-sided die is rolled. If the result is a prime number, a ball is drawn from Bag A, which contains 2 red and 3 blue balls. If the result is not a prime number, a ball is drawn from Bag B, which contains 4 red and 1 blue ball. What is the probability that the ball drawn is blue?

A bag contains 4 red balls, 5 blue balls, and 6 yellow balls. If one ball is drawn at random from the bag, what is the probability that the ball drawn is not red?

A card is drawn at random from a set of 15 cards numbered from 1 to 15. What is the probability that the number on the card is a multiple of 3 or a multiple of 5?

A box contains 12 identical white pens. If one pen is drawn at random from the box, what is the probability that the pen drawn is blue?

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

A box contains 5 red balls and 3 yellow balls. Two balls are drawn from the box one by one without replacement. Find the probability that the two balls drawn are of the same colour.

A fair six-sided die is rolled once.

a) What is the probability of rolling a number greater than 4?

b) What is the probability of rolling a number that is a multiple of 3?

A bag contains 5 marbles in total: 3 red (R) marbles and 2 blue (B) marbles. Two marbles are drawn from the bag sequentially without replacement.

(a) Calculate the probability that the first marble drawn is blue.

(b) If the first marble drawn was blue and not replaced, calculate the probability that the second marble drawn is red.