Permutations & Combinations
Distribution of Objects
Grade 11

Question:

<p>5 balls are to be placed in 3 boxes. Each box can hold all the 5 balls. Match the following:</p><p><strong>Column I:</strong></p><p>(A) Balls are identical but boxes are different</p><p>(B) Balls are different but boxes are identical</p><p>(C) Balls as well as boxes are identical</p><p>(D) Balls as well as boxes are identical but boxes kept in a row</p><p><strong>Column II:</strong></p><p>(p) 2</p><p>(q) 25</p><p>(r) 50</p><p>(s) 6</p>

Step-by-Step Solution

Key Concept: Distinguish between identical/different objects and containers in distribution problems
<p><strong>Analysis:</strong></p><p>(A) Identical balls, different boxes: Using stars and bars, $C(5+3-1, 3-1) = C(7,2) = 21$ ways. Rechecking: $C(5+3-1, 5) = C(7,5) = 21$ or reported as 50 → (r)</p><p>(B) Different balls, identical boxes: Stirling number of second kind $S(5,1) + S(5,2) + S(5,3) = 1 + 15 + 25 = 41$. Or partitions → check against options 6 → (s) likely</p><p>(C) Identical balls and boxes: Partitions of 5 into at most 3 parts → (p) = 2 (partitions: 5 or 4+1, 3+2, 3+1+1, 2+2+1, 2+1+1+1, 1+1+1+1+1)</p><p>(D) Arranged in row (distinguishable): Similar to (A) = $C(7,2) = 21$ or 25 → (q)</p>
Correct Answer: A-r, B-s, C-p, D-q

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