Final answer:
The number of surfers at each beach in Miami that have more than 75% of the beaches is 50.
Step-by-step explanation:
To determine the number of surfers at each beach in Miami that have more than 75% of the beaches, we need to look at the upper quartile (Q3) of the box plot. The upper quartile represents the 75th percentile. Looking at the box plot, we can see that the upper quartile is between 40 and 50, leaning towards 50. Therefore, the answer is (d) 50.