(iii) Total number of cards which are black and a king card is $2$
As We know that, Probability = Number of favorable outcomes/ Total number of outcomes
Therefore, the probability of getting a black card and a king is $2/52=1/26$
(iv) A jack, queen or a king are $3$ from each $4$ suits.
Thus, the total number of a jack, queen and king are $12$.
As We know that, Probability = Number of favorable outcomes/ Total number of outcomes
Therefore, the probability of getting a jack, queen or a king is $12/52=3/13$