I got E as the answer.

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.
[/spoiler]
Let me know what you think.

Hi gmatboost ,

This is exactly what I want - A very detailed explanation and ofcourse you are right . The answer is C . Thanks a lot.

I am happy it helped.

I am worried though that my images are cut off on the right-hand side. When you reply to the post you can see the images in their entirety, but on the post itself, it looks like the right-hand "Total" column is not visible.

There is a 1 in the bottom-right hand cell (Total-Total) in all images, because we know the total is 100%.

In images 4 and 5, there should be a 0.6 in the top-right cell, a 0.4 in the middle-right cell, and a 1 in the bottom-right cell. 0.6 represents the total "Older than 40" (0.3 + 0.3), and 0.4 represents the total "Under than 4 ," calculated as Overall Total - Older than 40 Total = (1 - 0.6).