When you see a question that classifies people or objects along two dimensions, you should immediately draw a chart that looks like this:
The 1 in the bottom right represents means 100% of the members. If actual numbers (as opposed to percentages) were given, we would use those, and we wouldn't necessarily put anything in the bottom right. You could plug in numbers here, but there's really no reason to do so.
Once you have that, you should plug in what you are given and what you are looking for:
Now, let's go through each statement. Remember that you'll have to delete, erase, or ignore whatever you learn in St. 1 when you consider St. 2.
Statement 1 says that half of females are over 40. This means that the other half of females are under 40. So, these cells should be equal. Filling in 0.3 in female under 40 allows us to fill in a few other cells too:
Conclusion: [spoiler]Unfortunately, it's not enough to get what we need, so St. 1 is INSUFFICIENT.[/spoiler]
Statement 2 says that half of the people over 40 are men. This means that the other half of people over 40 are female. So, these cells should be equal. Filling in 0.3 in male over 40 allows us to fill in a few other cells too:
Conclusion: [spoiler]Again, it's not enough to get what we need, so St. 2 is also INSUFFICIENT.[/spoiler]
Combining the statements, we can fill in much more of the chart:
Conclusion: [spoiler]This allows us to find the value of the yellow cell. It is 0.1, or 10%. The answer is C.
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Let me know what you think.
