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joannabanana
- Master | Next Rank: 500 Posts
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I came across a DS question that goes something like this:
Committee X and Y have no common members. They combine to form committee Z. Does X have more members than Y?
The two statements then tell us that average age of X is 26 and of Y is 29, and that once formed the average age of Z will be 27.
My initial thought about this question was that the average for Z has been skewed more towards the average of X, therefore X must have more members. (I wasn't sure if that was a correct assumption so I solved the problem with algebra.) Is this in fact a correct assumption? And is there an official way of stating it so that I can always remember it?
(If anyone is wondering this is Question 141 in OG.)
Committee X and Y have no common members. They combine to form committee Z. Does X have more members than Y?
The two statements then tell us that average age of X is 26 and of Y is 29, and that once formed the average age of Z will be 27.
My initial thought about this question was that the average for Z has been skewed more towards the average of X, therefore X must have more members. (I wasn't sure if that was a correct assumption so I solved the problem with algebra.) Is this in fact a correct assumption? And is there an official way of stating it so that I can always remember it?
(If anyone is wondering this is Question 141 in OG.)
