The first term in the sequence above is , and each term thereafter is equal to twice the previous term. If is an integer, which of the following could NOT be the sum of the first four terms of this sequence?
Correct Answer: Option(a)
Solution: The first term in given Geometric series,
The common ratio
No. of terms,
Applying sum of GP formula,
If is an integer the sum of the first four terms of this sequence should be in multiple of .
Hence, option A is correct which is not a multiple of .