The ratio of boys to girls in a class is 5:3, find the probability of selecting at random a girl from the class

A fair coin is tossed three times. Find the probability of getting two head and one tail 

If the probability of an event occurring is x, what is the probability of the event not occurring?

Given the set A ={2, 4, 6, 8} and B = {2, 3, 5, 9}. 

If a number is picked at random from each of the two sets, what is the probability  that their difference is 6 or 7

Given the set A ={2, 4, 6, 8} and B = {2, 3, 5, 9}. 

If a number is picked at random from each of the two sets, what is the probability that their product is odd?

Given the set A ={2, 4, 6, 8} and B = {2, 3, 5, 9}. 

If a number is selected at random from set B. what is the probability that the number is prime

A box contains black, white and red identical balls. The probability of picking a black ball at random from the box is $\tfrac{3}{10}$  and the probability of picking a white ball at random is $\tfrac{2}{5}$. If there are 30 balls in the box, how many of them are red?

A bag contains 5 red and 4 blue identical balls. If two balls are selected at random from the bag, one after the other, with replacement, find the probability that the is red and the second blue 

A fair die is thrown two times. What is the probability that the sum of the scores is at least 10?

In an athletics competition, the probability that an athlete wins a 100 m race is $\tfrac{1}{8}$ and the probability that he wins in high jump is $\tfrac{1}{4}$. What is the probability that he wins only one of the events