Arithmetic Ability
Permutations and Combinations

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Q.

Find the number of ways in which 21 balls can be distributed among 3 persons such that each person does not receive less than 5 balls.

View Answer

Correct choice: A

Explanation:

Let x, y, z be the number of balls received by the three persons, then x≥5, y≥5, z≥5 and x+y+z=21 Let u≥0, v≥0, w≥0 then ∴ x + y + z =21 ⇒ u + 5 + v + 5 + w + 5 = 21 ⇒ u + v + w = 6 ∴Total number of solutions = 6+3−1C3−1=8C2=28
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