MCQEasyJEE 2026Applications of P&C

JEE Mathematics 2026 Question with Solution

The number of ways 1616 oranges distributed to 44 children, each gets at least one.

  • A

    403403

  • B

    384384

  • C

    429429

  • D

    455455

Answer

Correct answer:D

Step-by-step solution

Standard Method

Given: 1616 oranges are to be distributed among 44 children, and each child gets at least one orange.

Find: The number of possible distributions.

The oranges are identical and the children are distinct. This is a standard stars and bars problem with positive integral solutions.

For

x1+x2+x3+x4=16,xi1x_1 + x_2 + x_3 + x_4 = 16, \qquad x_i \ge 1

the number of ways is

(16141)\binom{16-1}{4-1}

So,

(153)\binom{15}{3}

Now,

(153)=15×14×133×2×1\binom{15}{3} = \frac{15 \times 14 \times 13}{3 \times 2 \times 1} =5×7×13= 5 \times 7 \times 13 =455= 455

Therefore, the required number of ways is 455455. The correct option is D.

Common mistakes

  • Using combinations of children instead of distributions of identical oranges. This is wrong because the objects are identical and the problem asks for positive integer solutions. Use the stars and bars formula for x1+x2+x3+x4=16x_1+x_2+x_3+x_4=16 with xi1x_i\ge 1.

  • Using (164)\binom{16}{4} or (163)\binom{16}{3} directly. This is wrong because at least one orange must go to each child first, so the correct count is (153)\binom{15}{3}, not a direct selection from 1616 oranges.

  • Applying the non-negative formula (n+r1r1)\binom{n+r-1}{r-1} without adjusting the condition. That formula is for xi0x_i\ge 0, but here the condition is xi1x_i\ge 1. For positive distributions, use (n1r1)\binom{n-1}{r-1}.

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