A box contains 10 black and 10 whie balls.The probability of drawing two balls of the same colour is :

1. 9/19
2. 9/38
3. 10/19
4. 5/19

the number of black balls = 10 and

the number of white balls = 10

total number of balls = 10+10 =20

the probability of drawing two balls of the same color 

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