Question
Question: Number of ways in which 25 identical balls can be distributed among Ram, Shyam, Sunder and Ghanshyam...
Number of ways in which 25 identical balls can be distributed among Ram, Shyam, Sunder and Ghanshyam such that atleast 1, 2, 3, and 4 balls are given to Ram, Shyam, Sunder and Ghanshyam respectively, is-
A
18C4
B
28C3
C
24C3
D
18C3
Answer
18C3
Explanation
Solution
First of all select 1 + 2 + 3 + 4 = 10 balls out of 25 identical balls and distribute them as desired. It can happen only in one way. Now let x1, x2, x3 and x4 balls are given to them respectively. (where x1, x2, x3, x4 ³ 0)
Its now one can get any number of balls
\ non negative integral solution of
x1 + x2 + x3 + x4 = 15
will be the number of ways so
15 + 4 –1C4–1 = 18C3