Bunuel wrote:
How many people bought TVs at the Electronics Depot?
(1) One out of every six Electronics Depot customers bought a TV.
(2) If four Electronics Depot customers are chosen at random there are 126 different groups of people that could be chosen.
\(? = P\,\,\,\,\left( {{\rm{\# }}\,\,{\rm{bought - TV - there}}\,\,{\rm{people}}} \right)\)
\(\left( 1 \right)\,\,P = {N \over 6}\,\,\,\left\{ \matrix{
\,{\rm{Take}}\,\,N = 6\,\,{\rm{customers}}\,\,\,\, \Rightarrow \,\,\,? = P = 1 \hfill \cr
\,{\rm{Take}}\,\,N = 12\,\,{\rm{customers}}\,\,\,\, \Rightarrow \,\,\,? = P = 2 \hfill \cr} \right.\,\,\,\,\,\,\,\,\,\,\,\left( {N = \# \,\,{\rm{customers}}\,\,{\rm{there}}} \right)\)
\(\left( 2 \right)\,\,C\left( {N,4} \right) = 126\,\,\,\,\, \Rightarrow \,\,\,\,\,N\,\,{\rm{unique}}\,\,\,\left( {{\rm{and}}\,\,N > 4\,\,{\rm{for}}\,\,{\rm{sure}}} \right)\,\,\,\,\,\left\{ \matrix{
\,{\rm{Take}}\,\,P = 1\,\,\,\, \Rightarrow \,\,\,? = 1 \hfill \cr
\,{\rm{Take}}\,\,P = 2\,\,\,\, \Rightarrow \,\,\,? = 2 \hfill \cr} \right.\)
\(\left( {1 + 2} \right)\,\,{\rm{unique}}\,\,N\,\, = 6P\,\,\,\,\, \Rightarrow \,\,\,\,\,P\,\,{\rm{unique}}\)
The correct answer is therefore (C), indeed.
We follow the notations and rationale taught in the
GMATH method.
Regards,
Fabio.
_________________
Fabio Skilnik ::
GMATH method creator (Math for the GMAT)
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