Question

A box contains 13 large marbles and 20 small marbles. Each marble is either green or white. 5 of the large marbles are green, and 13 of the small marbles are white. If a marble is randomly selected from the box, what is the probability that it is small or green? Express your answer as a fraction or a decimal number rounded to four decimal places.

Answer 1

The probability of selecting a small or white marble is 10/13

Explanation:

The total number of marbles is 15 + 11 = 26 marbles

The probability that we want to calculate is if the marble selected is small or white.

So we need to find the number of small marbles as well as the number of white marbles

We can construct a table to see the distribution of the marbles. Please check the attachment for this.

From the table , we can see that there are 11 small marbles and a total of 9 white marbles

The probability of selecting a white marble is;

number of white marbles/total number of marbles = 9/26

The probability of selecting a small marble will be ;

number of small marbles/total number of marbles = 11/26

In probability, whenever we have or, we tend to add

So therefore, the probability of selecting a white or small marble = Probability of selecting a white marble + Probability of selecting a small marble

Mathematically, that would be 9/26 + 11/26 = 20/26

So the probability is 10/13