We will use geometric probability. The probability of an event represented by a segment of a number line is the ratio of the length of the segment representing the event to the length of the entire line. The length of the entire line is 30. Since 33 % is approximately 13, we want our event to be represented by a segment with a length equal to 13 of the length of the entire line.
1/3* 30 = 10
We want our event to be represented by a segment that has a length of 10. An example of such an event is randomly choosing a number between 10 and 20.
