(iii) Total number of black balls are $5$
We know that the Probability = Number of favorable outcomes/ Total number of outcomes
Therefore, the probability of drawing black ball P(E) $=5/15=1/3$
As We know that sum of probability of occurrence of an event and probability of non-occurrence of an event is $1$.
$P(E)+P(\overset{\scriptscriptstyle\rightharpoonup}{E})=1$
$\frac{1}{3}+P(\overset{\scriptscriptstyle\rightharpoonup}{E})=1$
$P(\overset{\scriptscriptstyle\rightharpoonup}{E})=1-\frac{1}{3}$
$P(\overset{\scriptscriptstyle\rightharpoonup}{E})=\frac{2}{3}$
Hence, the probability of drawing a ball that is not black is $2/3$
(iv) Total number of red or white balls $4+6=10$
As We know that Probability = Number of favorable outcomes/ Total number of outcomes
Hence , the probability of drawing a white or red ball $=10/15=2/3$