Q79 / 180 · COMEDK 2017 · Mathematics

In how many ways can 4 red, 3 yellow and 2 green discs be arranged in a row, if the discs of the same colour are indistinguishable?

  • A
    1200
  • B
    1220
  • C
    1240
  • Correct answer
    D
    1260

Solution

Total number of dises are $4+3+2=9$. Out of 9 dises, 4 are of the first kind (red) 3 are of the second kind (yellow) and 2 are of the third kind (green). Therefore, the number of arrangements $=\frac{9 !}{4 ! 3 ! 2 !}=1260$

Hence, the correct answer is option: 'D'.

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