BTGmoderatorDC wrote:If the 3rd term of sequence A is 15 and all of the terms in the sequence are positive, then what is the 2nd term?
1) The 1st term of A is 5.
2) Each term of A after the 1st term is y times the preceding term.
OA C
Source: EMPOWERgmat
Let's take each statement one by one.
1) The 1st term of A is 5.
Since the relationship between the 1st term and the 3rd term is not given, we can't get the 2nd term. Insufficient,
2) Each term of A after the 1st term is y times the preceding term.
Say the first term is a. Thus, the 2nd term = ay and the 3rd term = ay^2. Thus, ay^2 = 15. Since we have two variables a and y, we can't get their unique values, thereby can't get the value of the 2nd term ay. Insufficient.
(1) and (2) together
From (1), we have a = 5 and from (2), we have ay^2 = 15. Thus, ay^2 = 15 => 5*y^2 = 15 => y = √3
Thus, the 2nd term = ay = 5*√3. Sufficient.
The correct answer:
C
Hope this helps!
-Jay
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