BTGmoderatorDC wrote:The main ingredient in a certain prescription drug capsule cost $500 per kilogram. If each capsule contains 600 milligrams of ingredient, what is the cost of the ingredient in a capsule? (1 kilogram = 10^6 milligrams)
A. $0.30
B. $0.83
C. $1.20
D. $3.00
E. $3.33
Source: GMAT Prep
Perfect opportunity for UNITS CONTROL, one of the most powerful tools of our method!
$${\text{licit}}\,\,{\text{converters}}\,\,:\,\,\,\frac{{\$ \,500}}{{1\,\,{\text{kg}}}}\,\,\,\,\,;\,\,\,\,\,\frac{{1\,\,{\text{capsule}}}}{{600\,\,{\text{mg}}}}\,\,\,\,;\,\,\,\,\,\frac{{1\,\,{\text{kg}}}}{{{{10}^6}\,\,{\text{mg}}}}$$
$$?\,\,:\,\,\,\$ \,\,\,\,{\text{for}}\,\,\,1\,\,{\text{capsule}}$$
$${\text{?}}\,\,\,{\text{:}}\,\,\,\,1\,\,{\text{capsule}}\,\,\left( {\frac{{600\,\,{\text{mg}}}}{{1\,\,{\text{capsule}}}}} \right)\left( {\frac{{1\,\,{\text{kg}}}}{{{{10}^6}\,\,{\text{mg}}}}} \right)\left( {\frac{{\$ \,500}}{{1\,\,{\text{kg}}}}} \right)\,\,\,\, = \,\,\,\,\$ \,\,\frac{{500 \cdot 600}}{{{{10}^6}}}\,\,\, = \,\,\,\$ \,\,\frac{{30 \cdot {{10}^4}}}{{{{10}^6}}}\,\, = \,\,\,\$ \,0.3$$
This solution follows the notations and rationale taught in the GMATH method.
Regards,
Fabio. 
