What is the next number in the sequence 25, 27, 30, 15, 5, 7, 10?

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SUMMARY

The sequence 25, 27, 30, 15, 5, 7, 10 presents a challenge in determining the next number, which is concluded to be -5. Participants in the discussion highlight the complexity of identifying a definitive rule governing the sequence, emphasizing that without additional context or terms, multiple interpretations can arise. The initial assumption of a simple arithmetic pattern (+2, +3, divided by 2, etc.) is deemed insufficient, as the actual solution diverges from this reasoning.

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Drksilver163
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Hi,

so i am working on some basic math problems and i get this problem about finding the next number in the sequence, and this is it:

25, 27, 30, 15, 5, 7, 10 __


I see the simple solution as +2, +3, divided by 2, divided by 3, +2, +3, divided by 2 and so on...

So given my possible solution the answer should be 5, right? Wrong. Apparently the solution is -5. I don't see how this can be, unless I am missing something. Could the answer indeed be 5 and the negative is a typo? Any help would put my mind at ease, thanks.

Marco
 
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Welcome to PF!

Hi Marco! Welcome to PF! :smile:
​
Why divison?

Why not stay with addition and subtraction? :wink:
 
Drksilver163 said:
Apparently the solution is -5.
Do keep in mind that these kinds questions don't really have a "right" answer. Presumably the author had some rule in mind, but that rule cannot be known from just those 7 points of data. (In fact, it can't be known unless you know every term in the sequence!)

You shouldn't really feel bad that your guess was not what the author had in mind. But you should be able to field another guess now that you know what the next term actually is
 
tiny-tim said:
Hi Marco! Welcome to PF! :smile:
​
Why divison?

Why not stay with addition and subtraction? :wink:

I see...for some reason that thought didnt pop into my head cause whenever i look at these sequence problems i tend to over-think. Thanks a lot, this shows me to keep things more simple.

And thanks for the welcome :biggrin:

Hurkyl said:
Do keep in mind that these kinds questions don't really have a "right" answer. Presumably the author had some rule in mind, but that rule cannot be known from just those 7 points of data. (In fact, it can't be known unless you know every term in the sequence!)

You shouldn't really feel bad that your guess was not what the author had in mind. But you should be able to field another guess now that you know what the next term actually is

Thanks for your input as well. Seems to me like both can be a viable solution given the data points.
 
yep +2, +3, -15, -10, +2, +3, -15, -10
 

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