Answer 1

 5/84

Three balls can be drawn randomly from nine balls in ⁹C₃ = 84 ways.
Three balls cannot be red as there are only two red balls.
Three balls of the same colour can be drawn in the following ways :
3 blue out of a total of 3 blue balls.
The probability for which is \[\frac{^{3}{}{C}_3}{84} = \frac{1}{84}\]

3 black out of a total of 4 black balls.
The probability for which is \[\frac{^{4}{}{C}_3}{84} = \frac{4}{84}\]

Hence, required probability =\[\frac{1}{84} + \frac{4}{84} = \frac{5}{84}\]