chemistry conversion

Question

The average lethal dose of heroin is 150 mg/kg of body weight. How many grams of heroine would be lethal for a 200 lb man?

Answer 1

To convert mg to g, multiply the value by 1 g / 1000 mg:  150 -->  0.15 g

To convert kg to US lb, multiply by 2.205 lb / 1 kg:  1 kg  -->  2.205 lb

The lethal dose value will be 0.15 g / 2.025 lb = 0.0680 g/lb

So a fatal dose for a 200 lb person would be 200 lb (0.0680 g/lb) = 13.6 g