Latest CTS Aptitude Question SOLUTION: A secret can be told only 2 persons in 5 mins, the same person tells to 2 more persons and so on.In how many minutes will it reach 768 persons?

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A secret can be told only 2 persons in 5 mins, the same person tells to 2 more persons and so on.In how many minutes will it reach 768 persons?

Asked In CTS Punitha (8 years ago)

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anantatdas.dilan@gmailcom  (8 years ago)

Ans : 45 minutes.

This will form a binary tree. so the maximum numbers of nodes that can be formed by the tree is 2^(d+1) - 1 . where d is the depth of the tree.
So, the number 768 will come when d will be 9. That means (2^8+1 - 1) < 768 < (2^9+1 -1).
One depth takes 5 minutes. So, 9 depth will take 9 * 5 = 45 minutes.

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akhilesh kumar  (8 years ago)

47.5 minute
its like as 1,2,4,8,.....,256 the time taken as 45 min here and 2.5 min to take remaning person
so total answer is 47.5 min

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bobby  (8 years ago)

IN FIRST 5 MINUTE THE SECRET WILL SPREAD TO 3 PERSONS. IN NEXT 5 MINS IT'LL SPREAD TO 6 PERSONS...SIMILARLY 3,6,12,24,48,96,......IT TAKES 45 MINS OVERALL

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Streeteja  (8 years ago)

50 as it becomes expanding to the power two till 10

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SINDHUJA M  (8 years ago)

Ans: 50minutes

2=5min ->2person
2^2=10 min ->4person
2^3=15min ->8 person
2^4=20min ->16 person
2^5=25min ->32person
2^6=30min ->64 person
2^7=35min ->128person
2^8=40min ->256 person
2^9=45min ->512person
2^10=50min ->1024person
secret has to be conveyed to 768 persons it is b/w 512 and 1024 hence required is 50minutes.

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minku  (8 years ago)

ans 47.30s

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deekshith  (8 years ago)

for 1 person to 2 its 5 minutes.,
next 2 will tell two other two two.
so this order follows.
1+2+4+8+16+32+64+128+256=40 mins and rest 257 shoud take half of the 5 mints to tell the secret . so answer is 42.5 mints

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Chanchal Yadav  (8 years ago)

ANS: 50 because A binary tree has child 2^h-1=max no. of nods(768) where h= height of binary tree ,
solution :
2^9=512 ....... 9*5=45min
2^10=1024....... 10*5=50min
from 513 to 1024 it will take only 5 extra min
so 45+5=50

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DIVYA  (8 years ago)

person called in 5/2 min=2.5 min
then 768 person2.5*768=1920 min
32 hours

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anurag  (8 years ago)

Ans 50min.
2^1=2=5min
2^2=4=10min


2^9=512
2^10=1024
10*5=50

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Pavithra  (8 years ago)

ans : 47 min 5 sec

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Sowmya Ganti  (8 years ago)

i agree with Mr.anantatdas
but the calculation at the 9th level is wrong.
it takes (no. of nodes in the level*5mins per pair).
Hence , the answer is 1820 mins.

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vikramrapolu  (8 years ago)

45 min ...

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sundeep  (8 years ago)

2^x = 768

x = log(768) / log(2)

x = 9.5849

Then times that by the doubling time = 5 minutes

9.5849 * 5 = 47.9245 minutes = 47 minutes, 55.47 seconds

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Dhivya  (8 years ago)

47.5 is correct answer

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Naveen  (8 years ago)

The ans is 47.5 mins

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