Combining a Simple Presentation With a Complex One (IOD 502, 601, 701)

These questions look hard because the graph alone has too much going on: four or five curves, overlapping lines, a cluttered key. The table looks easy by comparison, just a short list of names or numbers. The trick is that the table is never decoration. It exists to cut the graph down to size, usually by telling you which one or two curves actually matter, or which rows of data you're even allowed to use. Once you see that job, the graph stops being overwhelming and becomes a lookup tool.

To make a plain table talk to a dense figure, scan both for a quantity that appears in each: a label, a species name, a depth, a temperature. That shared variable is the bridge. Find the value in the table first, since it's the simpler read, then carry it over to the axis or key in the figure where that same variable shows up. From there you locate the curve or point tied to it and read off whatever the question actually asks for, a rate, a percent, a concentration. Skip any curve or row the table didn't flag.

This builds directly on simpler interpolation and lookup skills, but adds a filtering step before you read anything. When three presentations show up instead of two, the logic just chains: use one to narrow the second, then carry that narrowed result into the third. The core move never changes, find the shared variable between whichever two pieces you're connecting at each step, and ignore any presentation, like an unrelated price or unrelated strain, that the question never asks you to use.