Walkabout wrote:

The inflation index for the year 1989 relative to the year 1970 was 3.56, indicating that, on the average, for each dollar spent in 1970 for goods, $3.56 had to be spent for the same goods in 1989. If the price of a Model K mixer increased precisely according to the inflation index, what was the price of the mixer in 1970 ?

(1) The price of the Model K mixer was $102.40 more in 1989 than in 1970.

(2) The price of the Model K mixer was $142.40 in 1989.

\({{{\rm{pric}}{{\rm{e}}_{\,70}}} \over {{\rm{price}}{\,_{89}}}} = {1 \over {3.56}}\,\,\,\,\,\,\left( * \right)\)

\(?\,\, = {\rm{pric}}{{\rm{e}}_{\,70}}\)

\(\left( 1 \right)\,\,\,{\rm{pric}}{{\rm{e}}_{\,89}} - {\rm{pric}}{{\rm{e}}_{\,70}} = 102.40\,\,\,\,\,\mathop \Rightarrow \limits^{\left( * \right)} \,\,\,\,3.56 \cdot {\rm{pric}}{{\rm{e}}_{\,70}} - {\rm{pric}}{{\rm{e}}_{\,70}} = 102.40\,\,\,\,\, \Rightarrow \,\,\,\,{\rm{SUFF}}.\,\)

\(\left( 2 \right)\,\,\,{\rm{pric}}{{\rm{e}}_{\,89}} = 142.40\,\,\,\,\,\mathop \Rightarrow \limits^{\left( * \right)} \,\,\,\,\,3.56 \cdot {\rm{pric}}{{\rm{e}}_{\,70}}\, = 142.40\,\,\,\,\, \Rightarrow \,\,\,\,\,{\rm{SUFF}}.\,\)

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

Regards,

Fabio.

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Fabio Skilnik :: https://GMATH.net (Math for the GMAT) or GMATH.com.br (Portuguese version)

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