AIM TO CRACK GMAT wrote:What comes next in the following series? 1/21, 1/14, 1/18, 1/16, 1/15, 1/18, 1/12, ......

[spoiler]OA= 1/20[/spoiler]

This would never be an actual GMAT question because it's possible to find more than 1 pattern in a set of numbers.
For example, what comes next in this sequence: 1, 2, 4, ... ?
Well, perhaps we're doubling each number, in which case the next value is 8
Or, perhaps we're adding 1, then 2, then 3 then 4 (etc), in which case the next value is 7

Likewise, for 1/21, 1/14, 1/18, 1/16, 1/15, 1/18, 1/12, ......, I could say that the correct answer is 3/17, because 1/21, 1/14, 1/18, 1/16, 1/15, 1/18, 1/12 are my 7 favorite fractions and 3/17 is my 8th favorite

Yes, I can see that having 7 values reduces the number of possible scenarios, but the rationale for why the GMAT would not test this still stands.

Cheers,
Brent

HI AIM TO CRACK GMAT,

As Brent has pointed out, this is NOT representative of what you'll see on the GMAT. It looks more like a 'brainteaser' from some type of puzzle/math book. If you're actually studying for the GMAT, then you should focus on realistic (and reputable) GMAT practice resources.

GMAT assassins aren't born, they're made,
Rich