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AP EAMCET · Maths · Permutation Combination

There are 7 identical white balls and 3 identical black balls. The number of distinguishable arrangements in a row of all the balls, so that no two black balls are adjacent is

  1. A 120
  2. B 89.(8!)
  3. C 56
  4. D 42×54
Verified Solution

Answer & Solution

Correct Answer

(C) 56

Step-by-step Solution

Detailed explanation

We will use Gap method to solve this. Firstly, 7 White balls can be arranged in 7! ways. But Since all balls are identical so it should be 7!7! ways. Now, A black ball can be between these white balls. So there are exactly 8 slots to place 3 black balls i.e.,…