Knowledge You Can Build On — Est. 1998
Labor Day Bonus Puzzle--Sequence
Alex Y
What is the next number in this sequence:
3 8 18 38 ?
There are two answers, one that was not suggested by the problem's author, but that I got, and therefore consider correct ;-)
and another cooler one suggested by the problem's author.
Re: Labor Day Bonus Puzzle--Sequence
Henry Higginbotham
78 looks like one.
Re: Labor Day Bonus Puzzle--Sequence
Larry Barrett
78
Re: Labor Day Bonus Puzzle--Sequence
Alex Y
That's the one I got, and I'd argue, along with you, that that is the best. Of course any of these sequence problems can have multitudinous answers, and it is a judgement call as to which is the best.
In the spirit of The Hitchhikers Guide to the Universe, someone has figured out how 42, the answer to life. the universe, and everything is an answer: The nth term of this sequence is given by the formula
f(n) = -(31/24)n^4+(55/4)n^3-(1145/24)n^2+(285/4)n-33
I don't know how I missed that one! Someone obviously has too much time on their hands.
The solution of 78 implies that if the sequence was extended to the left, the next term would be 1/2.
Can you think of a sequence where 1 is added as the first (leftmost) term?
1 3 8 18 38 ?
This one is not a mathematical formula.
Hint
Alex Y
We all agreed with the completion of the first sequence:
3 8 18 38 78
But what if the sequence is
1 3 8 18 38 ????
I'd bet good money that with this hint you will be able to get the answer.
Hint: this puzzle is US-centric.
Re: Labor Day Bonus Puzzle--Sequence
david weaver
88 would be my guess, but the pattern is obscure.
Correct!
Re: Correct!
david weaver
I'm admittedly dense. What's the US-centric part?
Re: Correct!
Larry Barrett
I think the word ‘bet’ has something to do with it, and the next term after 88 must be 188.
Re: Correct!
Alex Y
Yes, and the bet was good money in US currency.
Now, how did David come up with 88?
Re: Correct!
david weaver
The first three numbers are the first digits of the last three, with 8 as the second digit.
I figured that may not be correct. I know fairly little about gambling and bets, though, so if seeing a pattern is dependent on knowing something about betting or a certain game, I'm out.
Re: Correct!
Alex Y
US currency, adding the next larger denomination of bill each time.
Re: Correct!
David Weaver
I should've seen that. I've got a stack of 2s. I figured that the pattern that I'd come up was not likely how you got the sequence, but sometimes one gets lucky.
