This topic explain what is combinations and how to apply them.

Lesson 1 of 4: Learning Outcomes

At the end of this lesson, you should be able to

• explain combinations
• compute combinations for different types of problems or scenarios.

Lesson 2 of 4: Introduction to Combinations (5 mins)

What is Combination?

In combination, order of arrangement is NOT important.

For example, my fruit salad is a combination of apples, grapes and bananas. We don't care what order the fruits are in, they could also be "bananas, grapes and apples" or "grapes, apples and bananas", its the same fruit salad.

Another example. Suppose there are 7 people in a room - Alice, Bob, Charlie, Daniel, Eden, Frank & Gabriel. You intend to form a team of 3 out of the 7. Notice that the order does not matter, ie having "Alice, Frank Deniel" is the same as "Frank, Daniel, Alice" or "Daniel, Alice, Frank" etc.

In summary, Combination is about selecting some objects from a group of objects where the order is not important.

Lesson 3 of 4: Combination Calculations (15 mins)

General formula for Combination:

Example 1:

3 different species of orchid are to be selected from 20 unique species for cross-breeding. How many possible selections can be made?

Example 2:

The manager of a marketing department wants to form a 4 person committee from the 15 employees in the department. In how many ways can the manager form this committee?