Don’t understand the answer given in this!
Hi Chaitanya,
Can you please check the question?
I dont think the question is right ?
Or else tell us the source of the question.
It’s from Gmat On The Go! I don’t have the link to the exact question.
Next time I’ll include the question URL too !
Hi Chaitanya,
We shall correct that question in the GMATonthego,
Posting the right question now,
The sequence is equal to (xn)/2
If any number in the sequence is not equal to zero and xn+1 = (xn ) /2 for all positive integers n, what is the value of x7?
(1) x5 = x1 – (15/16)
(2) x3 = 0.25
Now if you look at the question, it is clear,
if n =1 ,
then
x2 = (x1)/2
Similarly, x3 = (x2)/2,
Statement I is sufficient:
given , x5 = x1 – (15/16),
doing backwards we can get,
x1 = (x5) * 2^4
Because , x5 = (x4)/2 , whereas x4 = (x3)/2, similarly we can get x1 = (x5) * 2^4
Substituting in the statement we get,
(x5 – 2^4* x5) = -(15/16)
Solving we get,
x5 = 1/2^4
we can now easily get the x7
x7 = (x6)/2, whereas x6 =(x5)/2
So x7 = 1/2^6
So sufficient.
Statement II is sufficient:
We know x3 = 1/4
Similarly, we can do backwards and get x7 = 1/2^6
So the answer is D.
Hope it is clear.