fskilnik wrote:
GMATH practice exercise (Quant Class 15)
What is the difference between the areas of the squares ABCD and EFGC, in that order?
(1) The area of the shaded triangle CDE is 30.
(2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9.
\(?\,\, = \,\,{S_{{\rm{ABCD}}}} - {S_{{\rm{EFGC}}}}\)
(Click on the image to have it "zoomed"!)
\(\left. \matrix{
\left( {1 + 2} \right)\,\,\,\,? = \,{\left( {5k} \right)^2} - {\left( {3k} \right)^2} = 16{k^2} \hfill \cr
30 = {S_{\Delta {\rm{CDE}}}} = {{3k \cdot 5k} \over 2}\,\,\,\,\, \Rightarrow \,\,\,\,{k^2} = 4\,\,\, \hfill \cr} \right\}\,\,\,\,\, \Rightarrow \,\,\,\,\,? = 16 \cdot 4\,\,\,\, \Rightarrow \,\,\,\,{\rm{SUFF}}.\)
The correct answer is (C).
We follow the notations and rationale taught in the
GMATH method.
Regards,
Fabio.
POST-MORTEM: this problem is presented in our Quant Class 17 (not 15)... we thank our students for the correction!
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Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net