Could you please explain how (A) is correct? Since the curve of biologists' salary begin only at the end of physicists' salary, wouldn't the physicists as a collective have higher salaries than all biologists under study?

Nowhere in the question it is mentioned that physicists' curve begin where the biologists' curve ends. The two curve collides at the right bottom of biologists' curve, so it's possible that some biologists at the bottom may have higher salary then physicists at the bottom of the curve.The questions ask for the possible conditions which might be true and not for ones which must be.

Yeah all scientists are in the two peak distribution as shown above. Some biologists would have higher salaries than physicists.

Need Visualize explanation

I feel like the question is quite tricky. the info is not exactly clear

Could someone explain why C could also be correct please?

I'm not a big fan of this question. I don't think it represents what you'll see on test day.

On the GRE, "Graphical data presentations, such as bar graphs, circle graphs, and line graphs, are drawn to scale; therefore, you can read, estimate, or compare data values by sight or by measurement."

It looks to me like the curve has a clear beginning and ending.
The distance from $70,000 to $100,000 represents $30,000
Using this measurement, I would estimate that the curve begins at approximately $50,000 and ends at approximately $120,000.
So it looks like range of salaries is around $70,000

So I would say that answer choice C cannot be true

I suggest that we look at this chart as one combining three charts, two identical normal distribution bell curves and one symmetrical chart with mean falling between 70 and 100. The mean of combined chart is 85, and the range is 170. Definitely choice C is valid.

Choice B is true just by looking and checking bell curves of two distributions.

Choice A is also true, as the lower boundary of physicists salary is 100-70=30, and 70 is obtained from the difference 170-100. There is an overlap between the salaries of biologists and physicists.

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