If a number is drawn at random from the first 1000 positive

Question

If a number is drawn at random from the first 1000 positive integers, what is the probability of selecting a "refined" number?

(1) Any "refined" number must be divisible by 22
(2) a "refined" number is any even multiple of 11

swath20 · Answer

Even I got D, but OA is B, could somebody explain why B and not D

Rupstar · Answer

What question is this in the OG?
and what was the OA explanation...maybe some details are missing in the Q

faizaniftikhar83 · Answer

22 has 22,44,66,88,110,...
11 even are 22,,66,88,110,...

D

MA · Answer

agreed. that's why i was taking to much time to answer this question because D is obvious answer and a trap. the explanation is that:

from i, refined numbers could be, (suppose n=22), n, 2n, 3n, 4n, 5n, and so on or n, n+220, n+440, n+660, and so on..........

from ii, refined numbers can onlu be 11, 2X11, 3X11, 4X11 and so on.......

if this is the case only B is sufficient to answer ther question.

Antmavel · Answer

MA, From Statement 2, it can't be 11x3...it can just be 11x2, 11x4, 11x6...always even :wink:

Personally at first time I picked B just because the statement 1 says : Any "refined" number must be divisible by 22 it doesn't give the definition of a refined number, just tells you that any of them must be divisible by 22. Maybe a refined number is a number divisible by 6 so that 22 would not be a possible refined number but 66 could be...The statement 2 seems more like the official definition of what is a refined number : a "refined" number is any even multiple of 11 so that you can conclude B is sufficient... that's my feeling :idea:

MA · Answer

from i, refined number could be 22, 220, 440 or all multiples of 22.

from ii, refined numbers are all number that are even multiple of 11 i.e. 11x2n.

Antmavel · Answer

I didn't understand your previous post MA...however 11*3 as you said before in your first post is not correct, that was my first reaction. It has to be even...

Finally I think the OA should be A, we don't need B. Any number that is divisible by 22 is also an even multiple of 11.

mirhaque · Answer

Finally I think the OA should be D. Any number that is divisible by 22 is also an even multiple of 11. Therefore, both A & B says the same thing na?

nocilis · Answer

uh ...
This one plays with the definitions. It is a CR question combined with a DS

1)
 Any "refined" number must be divisible by 22  
does not mean  All numbers divisible by 22 is a refined number. 

2)
a "refined" number is  any  even multiple of 11

I think the definition of refined number seems complete here (?).

So B.

What is the source of the question? This is the first time I am encountering such a DS-CR question.

nocilis · Answer

mirhaque,
Even within first 1000 +ve integers, Statement 1  does not mean all n umbers that are divisible by 22 is a refined number .
 All it says that any refined number is divisible by 22 . There is a big difference between the two.

Vijo · Answer

Yes, she is right Statement 1 means that any A is B, which doesn't necessarily mean that any B is also A. May be according to statement I they are referring to refined nos as nos divisible by 44 or 88 and thus all refined nos will be divisible by 22. Thus the answer is B. Tricky language :wink:

swath20 · Answer

Thanks for your contributions everybody...Was a tricky one....

If a number is drawn at random from the first 1000 positive

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