A jar contains 4 red and 8 blue marbles a marble is drawn from the jar what is the probability that a red marble is drawn ?

There is a 1/3 chance that a red marble would be chosen.
To find out you put add up the marbles, so they will make 12 marbles.
Since there are 4 red you put 4/12.
4/12 simplified is 1/3.
So the chance of a red marble being picked is 1/3.