The urn contains 10 white, 15 black, 20 blue and 25 red balls. They took out one ball.

The urn contains 10 white, 15 black, 20 blue and 25 red balls. They took out one ball. what is the probability that this ball is white or black or blue?

First, put all the balls together and find out their total number: 10 + 15 + 20 + 25 = 70.

Now add the number of white, black and blue balls: 20 + 15 + 10 = 45.

Let’s find the probability that the ball will be blue, white or black: P = 45/70 = 9/14.

So our answer is 9/14.