It's a nice tricky prob.....
Even stem 2 confused me a little bit, here is how to solve...
From stem 1 : we can get x2=x2-1/2 (by taking j value more than 1)
=> x2=x1/2
and x3=x2/2; x4=x3/2 ; x5=x4/2 and so on...
But by knowing this we can't identify what is x1 or the first term.
x1 can be 32 then x2 would be 16 and x3 would be 8 and so on....
if x1 is 16 then x2 would be 8; x3 would be 4 and so on...
So insufficient.
From stem 2 we get x5=x4/x4+1 ,no help at all as we cant define the series.
Combining these two...
we know from (1) x5=x4/2 and from (2) x5=x4/x4+1
so x4+1=2 [comparing (1) and (2) ]
=> x4=2-1=1
then x3=2*x4=2
then x2=2*x3=2*2=4
so, x1=2*x2=2*4=8 (see that x5 would be x4/(x4+1)=1/1+1=1/2.
So ans is C.
Amit
