Latest Elitmus Aptitude Question SOLUTION: THE ARE 20 STUDENTS AND THEY NEED TO BE ALLOCATED INTO 3 CLASSROOMS.IN HOW MANY WAYS CAN THIS BE DONE 1.ASSUMING THAT THE STUDENTS ARE IDENTICAL 2.ASSUMING THAT THE STUDENTS ARE DI

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(#M40034458) ELITMUS Numerical Ability question permutaion Keep an EYE

THE ARE 20 STUDENTS AND THEY NEED TO BE ALLOCATED INTO 3 CLASSROOMS.IN HOW MANY WAYS CAN THIS BE DONE
1.ASSUMING THAT THE STUDENTS ARE IDENTICAL
2.ASSUMING THAT THE STUDENTS ARE DISTINGUISHABLE

Asked In Elitmus (10 years ago)

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Read Solution (7) :

RAKESH  (10 years ago)

1. 20 students have to be allocate in 3 identical classrooms
n=20,r=3
no. of ways=(n+r-1)C(r-1)= (20+3-1)C(3-1)= 22C2 = 231

2. 20 students have to be allocate in 3 DISTINGUISHABLE classroms
each student can be allocated in 3 ways so total
no. of ways = 3^20

Is this solution Helpfull? Yes (75) | No (9)  

NAOREM DINESH SINGH  (10 years ago)

1. For any identical related question, the ans. is 1(one)

2. 3^20

Is this solution Helpfull? Yes (4) | No (9)  

SANTANA PANDA  (10 years ago)

1. Like the possible solutions of the integral equations
x + y + z = 20 (z,y & z as three classrooms)
Arrange r = 20 possble combinations among n=3 elements.
There are H(n, r) = C(n+r-1, r) = C(22,20) = C(22,2)
=22*21/2 = 21*11 = 231
2. Each student has 3 choices, totally, there 3^20 ways.

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

Anoop  (10 years ago)

@NAOREM, with exclusion (no class can contain more than one student) then For any identical related question, the ans will be one.

Is this solution Helpfull? Yes (2) | No   

naveen babu  (10 years ago)

1.given that students are identical so....

it is 2^3-1=7

2.given that students are diffrent then
it can be done in n+r-1C3 ways 1.e 20+3-1 C 3-1 = 22C2 ways

Is this solution Helpfull? Yes (1) | No (13)  

Mukesh Nayal  (10 years ago)

@Naorem is correct

Is this solution Helpfull? Yes (1) | No (4)  

aditi bose  (10 years ago)

formula for the solutions:
for identical case : (n-r-1)C(r-1)
for distinguisale case: (n-r-1)P(r-1)

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