There is an unlimited supply of identical red, blue and green coloured balls. In how many ways can 15 balls be selected from the supply?
Explanation:
Let the number of red, blue and green balls selected be ‘r’, ‘b’ and ‘g’ respectively.
∴ r + b + g = 15
Since the balls of each color are identical, the question is same as distributing 15 identical objects in 3 distinct groups.
⇒ Number of ways = 15+3-1C3-1 = 136.
Hence, 136.
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