Latest TCS Aptitude Question SOLUTION: 15 students join a summer camp. every day 3 students are on duty after the school to clean classrooms. After the course it was found that every pair has been on duty exactly once.

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(#M40012454) TCS question Keep an EYE

15 students join a summer camp. every day 3 students are on duty after the school to clean classrooms. After the course it was found that every pair has been on duty exactly once. How many days does the course last for ?

Asked In TCS arushi tyagi (11 years ago)

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ruchita mantri  (11 years ago)

15c3= 15*14*13/3*2*1=455
there can be different pairs of 3 among 15 students so 15c3

Is this solution Helpfull? Yes (22) | No (13)  

subhajit dey  (11 years ago)

each student can make a pair with every other student in 15c2 ways, i.e. ((14*15)/2)=105. again, let no. of days be x.
th4, total no. of students working there = (3*x)
=> 3*x=105 => x=35 (ans)

Is this solution Helpfull? Yes (20) | No (7)  

satish srivastava  (11 years ago)

5 days.. there r 15 students n 3 student pair do the work only once then 15/3 = 5 days..

Is this solution Helpfull? Yes (13) | No (25)  

sai spandana  (11 years ago)

here is it necessary to take combination i didn't think so ans 5days

Is this solution Helpfull? Yes (5) | No (9)  

Rashmi Chouhary  (11 years ago)

total no. of pairs=15c2=105
total no. of pair working each day=105/3=35
no. of days camp lasted=105/35=3days

Is this solution Helpfull? Yes (4) | No (14)  

niki  (11 years ago)

answer should be 105days..

Is this solution Helpfull? Yes (4) | No (5)  

dheeraj verma  (11 years ago)

15/3..
=5 days

Is this solution Helpfull? Yes (3) | No (8)  

deepak srivastava  (11 years ago)

15c3
as 3 students are to be selected from 15.

Is this solution Helpfull? Yes (3) | No (3)  

varun singh  (11 years ago)

it is saying that out of 15student each possible pair that can be form out of 15 has done cleaning exactly once ..... so number of possible pairs that can be form out of 15 is 15c2=105. so total 105 pairs and in question 1 pair exactly once so total 105 days couse last

Is this solution Helpfull? Yes (3) | No (1)  

sai spandana  (11 years ago)

y so can u explain it

Is this solution Helpfull? Yes (2) | No (4)  

satish srivastava  (11 years ago)

let us say there r 15 students then
A B ( 13 way ) = 13 paired AB with other student
C D ( 11 way ) = 11 now paired CD with other remaining student
E F ( 9 way ) = 9 paired with EF
G H ( 7 way ) = 7 paired with GH
and so on
therefore 13+11+9+7+.....1 = 49 is the answer.. therefore 49 days the course last.

Is this solution Helpfull? Yes (1) | No (3)  

sakshi tangri  (11 years ago)

ans shud b 15c3=455

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rajkumardubey  (11 years ago)

15C3 IS THE CORRECT ANSWER.........

Is this solution Helpfull? Yes (1) | No   

satish srivastava  (11 years ago)

the options for these ques is a)35, b)45 c)105 and d)none of these .. so the correct answer for the que is ?????? . i got the same ques in the link-- ( http://learnwebdesigns.blogspot.in/2012/10/tcs-written-exam-guwahati.html )if anyone can bring the solution from the options mentioned are most welcomed.

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