Combinatorics

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Akash7
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Joined: Thu Mar 15, 2018 10:31 am
Location: Dhaka

Combinatorics

Unread post by Akash7 » Tue Mar 27, 2018 6:10 pm

In how many ways can COMPUTER be spelled by moving either down or diagonally to the right showed in the figure below?? :D
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Ragib Farhat Hasan
Posts: 37
Joined: Sun Mar 30, 2014 10:40 pm

Re: Combinatorics

Unread post by Ragib Farhat Hasan » Fri Oct 19, 2018 1:49 am

The answer should be 14.

NABILA
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Joined: Sat Dec 15, 2018 5:19 pm
Location: Munshigonj, Dhaka

Re: Combinatorics

Unread post by NABILA » Mon Dec 17, 2018 5:47 pm

HOW?????????????????????? :?: :|

NABILA
Posts: 27
Joined: Sat Dec 15, 2018 5:19 pm
Location: Munshigonj, Dhaka

Re: Combinatorics

Unread post by NABILA » Mon Dec 17, 2018 5:49 pm

HOW?????????????????????? :?: :|

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samiul_samin
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Joined: Sat Dec 09, 2017 1:32 pm

Re: Combinatorics

Unread post by samiul_samin » Thu Jan 10, 2019 9:45 am

Count carefully acclrding the question.

NABILA
Posts: 27
Joined: Sat Dec 15, 2018 5:19 pm
Location: Munshigonj, Dhaka

Re: Combinatorics

Unread post by NABILA » Mon Jan 14, 2019 6:19 pm

I still can't understand.
Wãlkîñg, lõvǐñg, $mīlïñg @nd lìvíñg thě Lîfè

SMMamun
Posts: 56
Joined: Thu Jan 20, 2011 6:57 pm

Re: Combinatorics

Unread post by SMMamun » Wed Jan 16, 2019 8:42 pm

If repeated letters distract you, replace these in the following way, because the question basically asks you to choose and count properly:

A
B C
D E F
G H I J

From A, you have 2 choices: AB and AC (one down and the other right-down diagonally).
From each of AB and AC, you have also 2 choices: ABD, ABE and ACE, ACF. Total count up to the third row is, therefore, 4 or (2 × 2)
From each of ABD, ABE, ACE, and ACF, you have also 2 choices.

Can you see a pattern now and complete? :)

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