Final answer:
Without the actual graph mapping trunk diameters to tree ages for horse chestnuts and aspens, an exact answer cannot be provided. Generally, one can approximate the age difference by finding the intersection points of 35 inches diameter with each tree's growth curve and calculating the vertical (age) difference.
Step-by-step explanation:
To approximate the age difference between the horse chestnut and the aspen trees given a diameter of 35 inches, we would need to consult a graph that plots trunk diameter against tree age for both species. If we had access to the actual graph, we would look along the horizontal axis (representing trunk diameter) until we find the point that corresponds to 35 inches. At that point, we would then look at where the lines for each species intersect the vertical line drawn from 35 inches. We would then note the ages on the vertical axis (representing tree age) where these intersections occur for the horse chestnut and the aspen. The difference in these age values would tell us how many years older the horse chestnut is than the aspen.
Without the actual graph, an accurate answer cannot be provided. However, typically, such a graph would show that the horse chestnut grows more slowly in diameter as compared to the aspen. Therefore, given a similar trunk diameter, the horse chestnut would generally be older than the aspen. The exact age difference could typically be deduced by the difference in the vertical axis values at the 35 inches diameter intersection point.