Question

How many combinations of 4 objects are there,taken 2 at a time

Answer 1

Given:

Combination of objects 4 objects taken two at time

To find:

How many combinations can be made with selecting two at a time.

Explanation:

Combination of n things taking r at a time,

`^nC_r=(n!)/(\left(n-r\right)!r!)`

Solution:

Combination of 4 objects taking 2 at a time,

`\begin{gathered} ^4C_2=(4!)/(\left(4-2\right)!2!) \\ =(4!)/(2!2!) \\ =6 \end{gathered}`

This is the required answer.