swerve wrote:Anna wants to distribute chocolates among her four children in the ratio 1/2 : 1/5 : 1/6 : 1/12. How many minimum chocolates should she buy, so that she can distribute the chocolates in the given ratio?
A. 30
B. 45
C. 57
D. 90
E. 120
Source: e-GMAT
\[? = \min \left( {{\text{Total}}} \right)\]
\[\frac{1}{2}\,\,:\,\,\frac{1}{5}\,\,:\,\,\frac{1}{6}\,\,:\,\,\frac{1}{{12}}\,\,\,\,\mathop \Leftrightarrow \limits_{:\,\,60}^{ \cdot \,\,60} \,\,\,\,30:12:10:5\]
\[\left\{ \begin{gathered}
{\text{Child}}\,1 = 30k \hfill \\
{\text{Child}}\,2 = 12k \hfill \\
{\text{Child}}\,3 = 10k \hfill \\
{\text{Child}}\,4 = 5k \hfill \\
\end{gathered} \right.\,\,\,\,\,\,\,\,\left( {k > 0} \right)\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,Total = 57k\,\,\,\,\,\,\mathop \Rightarrow \limits^{k\,\,\operatorname{int} \,\,\left( * \right)} \,\,\,\,\,\,? = \min \,\,\left( {{\text{Total}}} \right)\,\,\, = \,\,57 \cdot 1 = 57\]
$$\left( * \right)\,\,\,\,\left\{ \matrix{
5k\,\, = {\mathop{\rm int}} \hfill \cr
2k = 12k - 10k\,\, = \,\,{\mathop{\rm int}} - {\mathop{\rm int}} = {\mathop{\rm int}} \hfill \cr} \right.\,\,\,\,\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,\,\,\,\,k = 5k - 2 \cdot \left( {2k} \right) = {\mathop{\rm int}} - 2 \cdot {\mathop{\rm int}} = {\mathop{\rm int}} $$
This solution follows the notations and rationale taught in the GMATH method.
Regards,
Fabio.