Need help on Tree Diagrams

[Nipuna]

What is the Difference of these 2? They Both look same to Me

treediagrams.jpg (58.62 KiB) Viewed 18590 times

[Saman]

Okay, All these are coming under the heading Permutations & combinations.

Here are the Wiki articles on this subject.
Permutation
Combination

See following video tutorials under Discrete Mathematical Structures Tutorial

Lecture-27 - Permutations and Combinations
Lecture 28 - Permutations and combinations
Lecture 29 - Permutations and Combinations (Contd...)

[Rksk]

Nipuna,

we learn this in the O/L class. i'm going to give you two examples.

01. there are two balls named A and B in a box. we take one from the box randomly. then return it back and get a ball randomly for the second time. the result will be A or B eveytimes.

02. there are three balls named A, B and C in a box. you get one from them randomly and don't return it. then get another and don't return. if you got A for first time, you wont get A in the second time. there are only B and C in the box. then if you got C in the second time, now only B is in the box. so you will got B in the third time surly.

think understood.


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[Nipuna]

Thanks Friend For the Reply.

After My O/L Exam I didn't remind any O/L stuff. So I forgot Almost all the O/L Stuff

[Neo]

Rksk and Nipuna,

This is not about Probability (?????????).

This subject is clearly Permutations & Combinations (????? ?? ??????) as correctly stated by Saman.

I think Nipuna has enough theories to learn. I'll put my answers (As I remember them) later.

[Herath]

Neo, What do you think about first tree?. Just A and B but.... I am just confused. could we select r amount of items from n number of items where r>n?.
I am going crazy..... counting has never been an easy thing for me. Still it is hard for me to read large numbers at once

[Rksk]

Rksk and Nipuna,

This is not about Probability (?????????).

This subject is clearly Permutations & Combinations (????? ?? ??????) as correctly stated by Saman.

I think Nipuna has enough theories to learn. I'll put my answers (As I remember them) later.

Sorry about the mistake. I only wanted to explain the tree diagrames.

It seems, BIT syllabus starts from A/L theories. and Nipuna has to work hard to understand these theories. Because it seems, he hasn't got good lectures on these.

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[Neo]

Nipuna, I think you already had a look at Permutations & Combinations by now. To start with, Permutations & Combinations are very easy to learn. Only thing is you need to read the question very carefully and understand whether the question asks for a Permutation or a Combination. If the question is talking about selecting few items in order then it is permutation. If it is not talking about an order, then it is a combination.

Have a look at my simple description here. What is Permutations & Combinations?

If we consider the first tree about combination, lets apply the formula.
Note that as mentioned in my tutorial, here you were asked to select one letter from the set {A, B} 3 times.
²C₁ X ²C₁ X ²C₁ = 2 x 2 x 2 = 8
So there are 8 combinations possible with these 3 selections.

Neo, What do you think about first tree?. Just A and B but.... I am just confused. could we select r amount of items from n number of items where r>n?.

Herath, here we select 1 letter, 3 times from the same set {A, B}. I guess it is clear now.

The other tree is about a permutation as it is clearly stated. Note that once a letter is selected it is not repeatedly selected. That means we are going to select 3 letters from the same set.
³P₃ = 3! / (0!) = 3 x 2 x 1 / 1 = 6

Is it clear Nipuna? You can ask questions as much as you want

[Nipuna]

Thanks Friend.

I am going to a Funeral of one of my friends Sister's

I will read Again after I come.

BTW: Without You and ROBOT.LK I am Finished by Now.

[Nipuna]

I Read it well Now It's Clear.