Final answer:
The probability of drawing a black marble from a bag containing 6 red and 10 black marbles is 5/8.
Step-by-step explanation:
The question involves calculating the probability of drawing a black marble from a bag. Given that there are 6 red and 10 black marbles in the bag, the total number of marbles is 6 + 10 = 16. The probability of drawing a black marble is the number of black marbles divided by the total number of marbles, which is 10/16. This simplifies to 5/8, considering that both 10 and 16 are divisible by 2. Therefore, the probability that the marble would be black is 5/8, which corresponds to option 4 in the list provided.