1. A research scientist devised an apparatus to irradiate mice for radiobiology experiments which was based on the use of a Am-241 source. An experiment revealed that a dose of 10 Gy was required to kill 50% of a stock of mice. It was found that a dose of 131 Gy from a standard 200-keV X-ray source was required to kill 50% of a stock of mice. Determine the relative biological effectiveness of the Am- 241 based source.