Step 1 :For part a, we need to find the maximum mean weight of the passengers if the water taxi is filled to the stated capacity of 25 passengers. This can be calculated by dividing the total weight limit by the number of passengers. The calculation is \(\frac{3500}{25} = 140\) lb. So, the maximum mean weight is \(\boxed{140}\) lb.
Step 2 :For part b, we need to find the probability that the mean weight of 25 randomly selected passengers exceeds the value from part a. This is a problem of normal distribution. We can use the z-score formula to calculate the probability. The z-score is the number of standard deviations a particular data point is from the mean. In this case, we need to find the z-score for the mean weight from part a, and then find the probability that a randomly selected data point (passenger's weight) is greater than this z-score. The z-score is calculated as \(\frac{140 - 187}{\frac{35}{\sqrt{25}}} = -6.714285714285714\).
Step 3 :Using the z-score, we can find the probability that a randomly selected passenger's weight is greater than the z-score. This probability is approximately 1.0000.
Step 4 :Final Answer: The maximum mean weight of the passengers if the water taxi is filled to the stated capacity of 25 passengers is \(\boxed{140}\) lb. The probability that the mean weight of 25 randomly selected passengers exceeds this value is approximately \(\boxed{1.0000}\).