How to calculate the probability of Combinations

Daily Dose 034 | Probability and Statistics

How do you calculate the probability of Combinations?

Knowing how to calculate the probability of Combinations can be a tricky endeavor.

Often confused with Permutations, without a doubt, come exam day, you are going to see a problem (or problems) that will require you to form subsets of a larger group of items.

So will this be a win for you?

At Prepineer, we are going to make sure that it is.

In this video, we dive into a FE Exam Practice Problem in the subject of PROBABILITY AND STATISTICS, specifically learning how to find the number of COMBINATIONS of given a set of objects.

Key Definition

What is a COMBINATION?

A COMBINATION is a selection of objects where the order doesn’t matter.

For example, say we have three balls: one red, one white, and one blue.

If we wanted to see how many different variations of these balls we get after choosing 2 at a time, we find that we get:

red – white
red – blue

white – blue
white – red

blue – red
blue – white

But since order doesn’t matter, red – white and white – red are the same.

So that’s a single combination, which goes for the others as well.

So in reality, instead of 6, there are 3 COMBINATIONS.

From a textbook sense, we would first find the number of PERMUTATIONS (which is 6 for the above scenario) and divide it by the number of ways we can rearrange the PERMUTATIONS…meaning, pair them up as white – blue : blue-white, etc.

So if you are wondering…

How can I calculate the probability of Combinations?

Check out the video and see how we can go about solving this type of problem in the most efficient manner.

As always, with Love, Prepineer

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