Sequence

[Joy Shaha]

Q. Find the 12th term of the Series?
3,7,18,36,61,93....

[Brent@GMATPrepNow]

Q. Find the 12th term of the Series?
3,7,18,36,61,93....

Not a true GMAT question. The GMAT does not test our ability to find missing terms in a sequence unless the sequence is defined for us. The reason is that there's no way that we can definitively determine ONE (and ONLY ONE) pattern in a given sequence.

Consider this example: 1, 2, 4, __
What's the missing term here?
Well, if we read the sequence as doubling from one term to the next, the next term is 8
HOWEVER, if we notice that we keep adding successively larger integers to each term (i.e., add 1, then add 2, then add 3, etc.) the next term is 7

Likewise, (if we want to get a bit silly), we might look at your sequence (3,7,18,36,61,93...) and say that the 12th term is 8448. Why?
Because 3 is my wife's favorite number, 7 is my wife's 2nd favorite number, 18 is my wife's 3rd favorite number, ... and 8448 is my wife's 12th favorite number.

So, rest assured, you won't be required to find missing terms on a GMAT sequence, unless the sequence is defined for us.

Cheers,
Brent