Latest CTS Aptitude Question SOLUTION: It takes five minutes to pass a rumour from one person to two other persons. The tree of rumour continues. Find how many minutes does it take spread the rumour to 768 persons.

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It takes five minutes to pass a rumour from one person to two other persons. The tree of rumour continues. Find how many minutes does it take spread the rumour to 768 persons.

Asked In CTS (12 years ago)

Unsolved Read Solution (6)

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Read Solution (6) :

Pargat Pal Singh  (12 years ago)

After 5 mins ..... 3 persons will get rumour
After 10 mins .... 3*2+3= 9 persons will get
after 15 =5*3 min ......9*2+9 =27 = 3^3 persons will get news.
...
.....
after 5*6 mins ... 3^6 = 729 persons will get news
after 5*7 = 35 mins .... 3^7 persons will get news which will cover more than 768 persons.


so 35 mins.
or
As It takes five minutes to pass a rumour from one person to two other persons.
and It takes 2.5 minutes to pass a rumour from one person to one other person.
if proportional time is allowed, 30+2.5 = 32.5 mins.

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Tanuj Saini  (12 years ago)

47.5 min

5*9+2.5=47.5

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manish  (10 years ago)

Mr. Pargat pal singh ji.. Please don't give wrong solutions

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Alka  (12 years ago)

15min (reslly fast isnt it!!!!!)

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Alka  (12 years ago)

74.5m .......

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Rakesh Kumar Kohli  (12 years ago)

It will take 45 minutes to spread rumor to 768 persons.
Rumor will spread as :
(Initiator of rumor)1->2^1->2^2->2^3->2^4->2^5->2^6->2^7->2^8->2^9
The rumor will have to pass through 9 phases so it will take 45 (9*5) minutes.

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