Question

Quick I need help!
From a selection of 9 different colored notebooks, Tom can take a group of 3. How many groups of 3 did he have to choose from if repetition is allowed?

Answer 1

Im not too sure but i would say 27

Answer 2

The total selection will be 165 if Tom can take a group of 3 and repetition is allowed.

What are permutation and combination?

A permutation can be defined as the number of ways a set can be arranged, order matters but in combination, the order does not matter.

We have:

Total number of colored notebooks = 9

Tom can take a group of 3

So total number of selections is given by:

$= \rm _{n+r-1}^{}\textrm{C}_r$

Here n = 9, and r = 3

$= \rm _{9+3-1}^{}\textrm{C}_3\\\\= \rm _{11}^{}\textrm{C}_3$

= 165

Thus, the total selection will be 165 if Tom can take a group of 3 and repetition is allowed.

Learn more about permutation and combination here:

https://brainly.com/question/2295036

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