# Problem Solving

• July 19th 2011, 06:43 PM
tonysathre
Problem Solving
Find the letter that is the 118th entry in the following sequence. Explain how you determined your answer.

Y,R,R,Y,R,R,Y,R,R,Y,R,R,Y,R,R...

I know the answer is Y, but I can't figure out why.

Thanks,

Tony
• July 19th 2011, 07:43 PM
CaptainBlack
Re: Problem Solving
Quote:

Originally Posted by tonysathre
Find the letter that is the 118th entry in the following sequence. Explain how you determined your answer.

Y,R,R,Y,R,R,Y,R,R,Y,R,R,Y,R,R...

I know the answer is Y, but I can't figure out why.

Thanks,

Tony

The $n$th letter is Y if and only if $n \equiv 1 {\text{ mod }} 3$

CB
• July 19th 2011, 07:53 PM
tonysathre
Re: Problem Solving
I appreciate your reply, but I don't know what any of that means. I'm awful at math. I think the instructor is just looking for a basic answer on how to figure it out.
• July 19th 2011, 07:56 PM
pickslides
Re: Problem Solving
Well maybe you can say its the first letter, then every third letter.

So the pattern goes, 1, 4, 7, 10, ...
• July 19th 2011, 07:59 PM
tonysathre
Re: Problem Solving
Yeah that's what I had, but I didn't know if it made sense or if it was even an answer at all. Thanks again.