Question

There are a total of 21 marbles in the box. And 5 of the marbles

are black and 6 of them are blue. A single marble is chosen at
random from the box. What is the probability of choosing a
black ball or a blue ball?

Answer 1

Explanation:

there are in total 21 marbles.

5 black, 6 blue = 11 black or blue marbles.

so, the probability of pulling a black or blue marbles is as always desired possible outcomes / total possible outcomes = 11/21