A secret can be told only 2 persons in 5 minutes .the
same person tells to 2 more persons and so on . How long
will take to tell it to 768 persons ?
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Answer Posted / laughing man
First in an aptitude question students are expected to keep
their eyes open to the terms used in the question. Otherwise
an aptitude paper would be the same as that of a 6th or 7th
standard question paper. The original question here was "the
same person". So the same person tells it to different
couple of people taking 5 mins each. 768 person here, so
768/2=384,384*5=1920 should have been the answer.
Now, supposing its a typical maths question, i.e. assuming
all the above assumptions made in the earlier posted answers
to be true, its a simple GP series which starts from 1, then
2 then 4 then 8 and so on.
So, by the problem,
2^0 + 2^1 + 2^2 +....+ 2^n = 768 (note: the first person has
been counted in the series)
so putting the summation formula for GP
1.(2^(n+1)-1) / (2-1) = 768
=> 2^(n+1) = 769
Now, 2^9 = 512 (leaving 257 behind)
Again, the count of 5 mins will be n number of times cause
the first term, i.e. 2^0 is the first person and he already
knows the secret, so the count will start essentially after
him. So n+1=9 => n=8. And for the remaining 257(actually
256, as the first person is counted in it) will be told in
extra 2.5 mins. So total, 8*5 + 2.5 = 42.5
| Is This Answer Correct ? | 5 Yes | 4 No |
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