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Source: — Data Sufficiency |
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by Argen » Wed Jan 09, 2008 7:39 am
The answer is C.

The stem is asking whether sqrt(r^2+s^2)=sqrt(u^2+v^2)

1) We get some information on r and s but we don't know about u and v. So insufficient.

2) We can plug this information into the stem and get:
sqrt(r^2+s^2)=sqrt((1-r)^2+(1-s)^2)=sqrt(1-2r+r^2+1-2s+s^2)=sqrt(2-2(r+s)+r^2+s^2). This alone is also insufficient.

However, if we plug the information that r+s=1 into sqrt(2-2(r+s)+r^2+s^2), we get sqrt(r^2+s^2). Therefore C.
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