How do you find the probability of something?

Expert Answers
hala718 eNotes educator| Certified Educator

The probability is the chance that certain event may occur or not occur.

To calculate the probability you need to figure out the possible outcomes and then determine the event's outcomes.

For example:  in a regular die we need to find the probability of getting a (2)

First we need to determine what possible outcomes could occur from rolling the die which is: 1, 2, 3, 4, 5, or, 6

The total number of outcomes is 6.

Then the chance or the probability of getting a two is one to six , 1:6   or 1/6.

If we need the probability of getting an even number, first we determine the outcomes which is: 2, 4, 6

Then the chances for the even number to occur is 3 to 6 or 3:6

Then the probability = 3/6 = 1/2

neela | Student

Probabale event is a situation where event may happen or not. Probability  is always expressed in a measure from 0 to 1. For an event which cannot happen, the probability 0. For an event which certainly happens, the probaility is 1. We may also say probality in percentage also. The calculation and definition of probility is:

If there are n exhaustive and mutuallyexclusive and equally likelycases and m of them are favourable to an event A, the probability of the happening of  A is defined as a ratiom/n.

Example: A bag contains 3 green and 2 red balls. What is the probability that a randomly drawn ball is Black .  Answer is zero ,as there are no black balls. If it is to be green the probility of getting it is 3/5.

Hope this may help.

slcuster04 | Student

The probability of something is the number of possible solutions / the number of options.

A penny has 2 sides but only 1 of them is heads.  So the probability of throwing it and it landing heads up is 1(heads) : 2 (sides)

So if there was a bag of 8 Bertie Bott's jelly beans and 5 of them were banana flavor and 3 of them were rotten egg flavor, the probability of you getting a rotten egg is 3 (number of rotten egg jelly beans) : 8 (total number of possible choices).  

If you switched that same bag up and you were looking for the probability of getting banana flavor it would be 5:8 because there are 5 banana beans in the bag of 8 beans.

Probability can also be written as a fraction such as 3/8 or 5/8.