Problem Solving (PS) | Re: The letters D, G, I, I , and T can be used to form 5-letter strings as

gmatophobia

If one "I" is at the start or end, the second "I" will have 3 places to select from, other letters will be placed as 3*2*1 thus 3*3*2*1 = 18 ways if I at start. Similarly, 18 ways if "I" is at the end. Thus total of 18+18 = 36 cases

If I is at any other place, then the second "I" can't be placed at 2 neighboring places thus it will have 2 places to select from and rest of the numbers will be placed as 3*2*1
Now this first I can be at second position, third position or fourth the above case II logic will remain same and thus 3*3*2*1=18

Thus total of 36 + 18 = 54 ways.
Can you please help me understand the mistake I made.

Statistics : Posted by Rickooreo • on 15 Jun 2016, 00:51 • Replies 36 • Views 118829

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