## Question

The number of ways in which 20 different pearls of two colours can be set alternately on a necklace, there being 10 pearls of each colour is :

### Solution

Twenty pearls ≡ 10 pearls of one color and 10 pearls of another color

**Step I : **First arrange pearls of same color in 1/2 (10 – 1)!

= 1/2 × 9!

**Step II : **Now arrange pearls of another color in between the arranged 10 pearls in 10! Ways.

#### SIMILAR QUESTIONS

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