Elitmus
Exam
Numerical Ability
Permutation and Combination
Find the no. of ways u can fill 3*3 grid (with 4 corners a,b,c,d) if u have 3 white marbles and 6 black marbles.
Read Solution (Total 8)
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- 3*3= 9 grid
no. of marbles= 3+6=9
we have to fill 9 grid with 9 marbles in which 3 are white & 6 are black
no. of ways = 9!/3!*6! = 9C3 = 9C6 = 84 - 10 years agoHelpfull: Yes(15) No(1)
- 3*3 grid will be 9 grid.
so we have to fill 9 grid with 9 marbles.
firstly,3 white marbles will be filled in 9 grid by 9c3 ways.
again remaining 6 grid will be filled by 6 black marbles in 6c6 ways= 1 way.
total ways=9c3*6c6 = 84 ways - 10 years agoHelpfull: Yes(6) No(0)
- It is a 3*3 grid, so there are a total of 9 spaces where you can place the marbles. Let us first place the 3 white marbles, that can be done in 9C3 ways. There are 6 spaces available and 6 black marbles are to be placed in those 6 spaces. So, that can be done in 1 way.
Hence the answer would be 9C3.
- 10 years agoHelpfull: Yes(3) No(0)
- It is a 3*3 grid, so there are a total of 9 spaces where you can place the marbles. Let us first place the 3 white marbles,
that can be done in 9C3 ways. There are 6 spaces available and 6 black marbles are to be placed in those 6 spaces. So, that can be done in 1 way.
Hence the answer would be 9C3.
- 10 years agoHelpfull: Yes(1) No(0)
- 84 is the correct answer
no of black marbles=3 white 6
first of all place black let us say 1,2,3 rows in 1,1,1 this can be done in 3c1*3c1*3c1=27
next combination of black balls are (2,1,0) this can be donw in 3c2*3c1*3!=54 ways
final combination placing all three balls in one row like that we can arrange for remaining rows also , so it gives 3ways....
so total no of ways =27+54+3=84ways
- 10 years agoHelpfull: Yes(1) No(0)
- It is a 3*3 grid, so there are a total of 9 spaces where you can place the marbles. Let us first place the 3 white marbles, that can be done in 9C3 ways. There are 6 spaces available and 6 black marbles are to be placed in those 6 spaces. So, that can be done in 1 way.
Hence the answer would be 9C3.
- 10 years agoHelpfull: Yes(0) No(0)
- what's d use of 3*3 grid here.it may be directly 9 grid????
- 10 years agoHelpfull: Yes(0) No(0)
- there are total 9grids which are to be filled by 3 wht and 6 black marbles in 9! ways.. and 3 wht mrbles and 6 black marbles r idntcl. so no.of ways doing so is : (9!)/ (3!.6!)=84 ways.. so ans is 84
- 10 years agoHelpfull: Yes(0) No(0)
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