137) find value

[ern5231]

137) what is the value of a 15 / a 10?
(1) a 10 / a 5 = 32
(2) a n +1 / a n = 2

Subscripts are given in bold.

[ballubalraj]

Let me try to explain it based on my understanding:

Stmt 1: As it gives the values of 2 distant items (a5 and a10) of a list, we can not determine how the series is going to be for from a10 to a15. Although a5 to a10 and a10 to a15 are at same the distance in the series, but until we know the exact trend, we can not determine it. Hence, not sufficient.

Stmt 2: an+1/an = 2; as n is a variable here, it must be true for all of the series items. This statement clearly tells that the next item on the list is = 2 times the previous item. So, a15/a10 = 2x2x2x2x2 = 32. Hence sufficient.

Answer: B

(Subscripts are given in bold.)