The ratio of red balls, to yellow balls, to green balls in a basket is 2 : 3 : 4. What is the probability that a ball chosen at random from the basket is a yellow ball?

Question: The ratio of red balls, to yellow balls, to green balls in a basket is 2 : 3 : 4. What is the probability that a ball chosen at random from the basket is a yellow ball?

Solution:
The ratio of red balls, to yellow balls, to green balls in a basket is 2 : 3 : 4
let, there are 2x red balls, 3x yellow balls and 4x green balls
total balls = 2x + 3x + 4x
= 9x

∴ probability that a ball chosen at random from the basket is a yellow ball = 3x/9x
= 3/9
= 1/3