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← JEE Advanced 2026 · Paper 1
MathematicsNumerical+4Question 11 of 48

JEE Advanced 2026 · Paper 1, Mathematics question 11

The number of ways to distribute 1010 identical red pens and 1414 identical blue pens among four persons such that each person gets 6 pens, is ________.

Answer and worked solution

Official answer: 206

Once each person's red count rir_i is fixed, the blue counts 6−ri6-r_i follow. So count solutions of
r1+r2+r3+r4=10,0≤ri≤6.r_1+r_2+r_3+r_4=10,\qquad0\le r_i\le6.
(The blue total is then 24−10=1424-10=14 automatically.)

  • Without the upper bound: (133)=286\binom{13}{3}=286.
  • Some ri≥7r_i\ge7 (at most one can be): 4(63)=804\binom{6}{3}=80.

Answer 286−80=206286-80=206.