

Given there are 5 apples, 10 mangoes and 13 oranges.
Let x1 is for apple, x2 is for mango and x3 is for orange.
Now, first we have to select total 15 fruits out of them.
x1 + x2 + x3 = 15 (where 0 <= x1 <= 5, 0 <= x2 <= 10, 0 <= x3 <= 13)
= (x0 + x1 + x2 +.........+ x5 )*(x0 + x1 + x2 +.........+ x10 )*(x0 + x1 + x2 +.........+ x13 )
= {(1- x6 )/(1 - x)}*{(1- x11 )/(1 - x)}*{(1- x14 )/(1 - x)}
= {(1- x6 )*(1- x11 )*{(1- x14 )}/(1 - x)3
= {(1- x6 )*(1- x11 )*{(1- x14 )} * ∑ 3-r+1Cr * xr
= {(1- x11 - x6 + x17 )*{(1- x14 )} * ∑ 3+r-1Cr * xr
= {(1- x11 - x6 + x17 - x14 + x25 + x20 - x31 )} * ∑ 2+rCr * xr
= 1* ∑ 2+rCr * xr - x11 * ∑ 2+rCr * xr - x6 * ∑ 2+rCr * xr + x17 * ∑ 2+rCr * xr - x14 * ∑ 2+rCr * xr+ x25 * ∑ 2+rCr * xr + x20 * ∑ 2+rCr * xr- x31 * ∑ 2+rCr * xr
= ∑ 2+rCr * xr - ∑ 2+rCr * xr+11 - ∑ 2+rCr * xr+6 + ∑ 2+rCr * xr+17 - ∑ 2+rCr * xr+14 + ∑ 2+rCr * xr+25 + ∑ 2+rCr * xr+20 - ∑ 2+rCr * xr+25
Now we have to find coefficeien of x15
= 2+15C15 - 2+4C4 - 2+9C9 - 2+1C1 (rest all terms have greater than x15 , so its coefficients are 0 )
= 17C15 - 6C4 - 11C9 - 3C1
= 17C2 - 6C2 - 11C2 - 3C1
= {(17*16)/2} - {(6*5)/2} - {(11*10)/2} - 3
= (17*8) - (3*5) - (11*5) - 3
= 136 - 15 - 55 - 3
= 136 - 73
= 63
Again we have to distribute 15 fruits between 2 persons.
So x1 + x2 = 15
= 2-1+15C15
= 16C15
= 16C1
= 16
Now total number of ways of distriburtion = 16*63 = 1008
