Find the mean marks of students for the following distribution

A bag contains 24 balls of which x are red, 2x are white and 3x are blue. A ball is selected at random. What is the probability that it is

(i) not red?

(ii) white

At a fete, cards bearing numbers 1 to 1000, one number on one card, are put in a box. Each player selected one card at random and that card is not replaced. If the selected card has a perfect square greater than 500, the player wins a prize. What is the probability that

(i) the first player wins a prize?

(ii) the second player wins a prize, if the first has won?

Determine the mean of the following distribution

Find the mean age of 100 residents of a town from the following data.