Combinatorics
Combinatorics
In how many ways can COMPUTER be spelled by moving either down or diagonally to the right showed in the figure below??
 Attachments

 com.JPG (12.94 KiB) Viewed 3731 times

 Posts: 62
 Joined: Sun Mar 30, 2014 10:40 pm
Re: Combinatorics
The answer should be 14.
Re: Combinatorics
HOW??????????????????????
Re: Combinatorics
HOW??????????????????????
 samiul_samin
 Posts: 1007
 Joined: Sat Dec 09, 2017 1:32 pm
Re: Combinatorics
Count carefully acclrding the question.
Re: Combinatorics
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 rightdown 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?
A
B C
D E F
G H I J
From A, you have 2 choices: AB and AC (one down and the other rightdown 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?