3. the red ball is a 0.5 chance (since 2 of the 4 are red, or 1/2)
the blue ball is a 0.5 chance (since 2 of the 4 are blue, or 1/2)
the yellow is a 0 chance (since there's no yellow)
4. the white ball is a 0.666... or 2/3 chance (since 2/3 are white)
the black ball is a 0.333... or 1/3 chance (since 1/3 are white