Asifpirlo wrote:
A village is under attacked by a deadly virus species. The virus is spreading greatly. But there is a talented scientist who can put this virus under control, but to do so all he needs to know is “does the population of the viruses double everyday?”
(1) The population increased by 12 on a particular day.
(2) The population increased by 18 on a particular day.
Good Question
The questions asks whether "r " in a geometric sequence is 2 or notLets assume that r=2
& first term is x
So the sequence will be
x 2x 4x 8x 16x 32x 64x 128x
So the increases on any particular day can be x, 2x, 4x, 8x, 16x, 32x, 64x
Statement 1The population increased by 12 on a particular day.
Clearly insufficient as 12 can equal any one of the terms in x, 2x, 4x, 8x, 16x, 32x, 64x
Statement 2The population increased by 18 on a particular day.
Clearly insufficient as 18 can equal any one of the terms in x, 2x, 4x, 8x, 16x, 32x, 64x
Statement 1 & 2The population increased by 12 & 18 on two different days.
12 can equal any one of the terms in the following sequence x, 2x, 4x, 8x, 16x, 32x, 64x
12......Value of x........Proportionate value of 18 (in terms of x)............Is there any increase in the sequence that equals Proportionate value of 18 (in terms of x)
x........12...................1.5x................................................................No
2x.......6....................3x...................................................................No
4x.......3....................6x...................................................................No
8x.......1.5.................12x..................................................................No
16x.....3/4.................24x..................................................................No
This clearly proves that "r " in a geometric sequence is not 2
Thus Sufficient
Answer C
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