Question

How many strings of length 6 over the alphabet {A, B, C} have at least 5 consecutive A’s? { solve by mutual exclusion} closed

Answer 1

A = String starting with 5 consecutive A  of length 6 => 1*1*1*1*1*2 => 2

B =  String starting with 6 consecutive A  of length 6 => 1*1*1*1*1*1 => 1

is answer = 3 ??

Comments

it will be $5$

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A = String starting with 5 consecutive A  of length 6 => 2*1*1*1*1*1  +  1*1*1*1*1*2 = 4  @ joshi_nitish  now 5 will come 

B =  String starting with 6 consecutive A  of length 6 => 1*1*1*1*1*1 => 1

4+1 =5   {what is your approach }

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same as yours(later one), former one is wrong

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thanks yes i missed one case previously