At the Trenchard Oaks apartment complex, a two-bedroom apartment costs

Hi All,

We're told that a two-bedroom apartment costs 50% more to rent than a one-bedroom apartment. If Alex were to rent a two-bedroom apartment for X months it would cost him the same amount as it would to rent a one-bedroom for 12 months. We're asked for the value of X. This question can be solved in a couple of different ways. TESTing VALUES works really well (as ArjunJag1328 has shown); it can also be solved by TESTing THE ANSWERS.

Since a two-bedroom apartment costs 50% more than a one-bedroom apartment, we need to find a value for X that, when increased by 50%, equals 12. Since a 50% increase is NOT the same as DOUBLING a value, we can eliminate Answer A. Let's TEST Answer B first.

Answer B: 8 months
IF... X = 8, then 50% MORE than 8 would be (1.5)(8) = 12
This is an exact match for what we were told, so this must be the answer.

Final Answer:

GMAT assassins aren't born, they're made,
Rich

\(? = x\)

Trivial application of UNITS CONTROL, one of the most powerful tools of our course:


\(\left. \matrix{\\
{\rm{one - bed}}\,\,\,:\,\,\,\,{{\$ \,\,2d} \over {1\,\,{\rm{month}}\,}}\,\,\,\,\,\,\,\, \to \,\,\,\,\,\,12\,\,{\rm{months}}\,\,\,\left( {{{\$ \,\,2d} \over {1\,\,{\rm{month}}\,}}} \right)\,\,\, = \,\,\,\$ \,\,24d\,\,\,\,\, \hfill \cr \\
{\rm{two - bed}}\,\,:\,\,\,{{\$ \,\,3d} \over {\,1\,\,{\rm{month}}\,}}\,\,\,\,\,\,\,\, \to \,\,\,\,\,\,x\,\,{\rm{months}}\,\,\,\left( {{{\$ \,\,3d} \over {1\,\,{\rm{month}}\,}}} \right)\,\,\, = \,\,\,\$ \,\,3xd \hfill \cr} \right\}\,\,\,\,\,\,\,\mathop \Rightarrow \limits^{{\rm{stem}}} \,\,\,\,\,\,\,24d = 3xd\,\,\,\,\,\,\mathop \Rightarrow \limits^{d\,\, \ne \,\,0} \,\,\,\,\,\,\,? = x = 8\)


This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.

We can let the cost to rent a one-bedroom apartment per month = n. Therefore, the cost for a two-bedroom apartment per month = 1.5n; thus:

1.5nx = 12n

1.5x = 12

x = 8

Answer: B