(iii) Total number of black balls is $5$
As We know that, Probability = Number of favorable outcomes/ Total number of outcomes
Therefore, the probability of getting a black ball $=5/12$
(iv) Total number of balls which are not red are $4$ white balls and $5$ black balls i.e. $4+5=9$
As We know that, Probability = Number of favorable outcomes/ Total number of outcomes
Therefore, the probability of getting no red ball $=9/12=3/2$