Final answer:
The value of 's' that makes the conditional probability of drawing a white ball on the third draw 3/4, given that there are 3 white balls in the sample of 4, is 3. The calculation is based on the proportion of white balls in the sample size, which leads to the equation 3/4 = s/4, solving for 's' gives s = 3.
Step-by-step explanation:
The question is asking to find the value of 's' for which the conditional probability that the ball drawn on the third draw was white, given that the sample contains 3 white balls, is 3/4. In this context, 's' should represent the number of successful outcomes that satisfy this condition.
Since the problem states that the sample of size 4 contains 3 white balls out of the 8 white balls initially present in the urn, and since there is no information indicating otherwise, we will assume that 's' is the number of ways to pick 3 white balls when 3 of the 4 balls in the sample have been determined to be white.
To solve this problem, we need to calculate the conditional probability using the information given. The third ball being white is one of the 3 white balls in the sample.
So, the probability that the third ball is white, knowing that there are 3 white balls in the sample, is simply the number of white balls divided by the sample size. Without knowing specific details about the draws, we assume that each draw is equally likely, so the probability is simply the proportion of white balls, which is s/4.
Given that 3/4 is the stated probability, we can infer that 's' must be 3 to satisfy the equation (3/4 = s/4), where s is equal to 3.
Thus, the correct answer is c. 3.