In a nuclear incident, for 10 hours, a nuclear worker with a mass of (70+ LDSN) kg was exposed to a monoenergetic gamma source of 137Cs with an activity of 5 Ci (E, =662 keV). 1. At 100 cm from the source, 10% of all gamma emitted by the source have been fully absorbed in his body, what is his total absorbed dose, D? 2. What is his absorbed dose rate (per hour)? 3. What is his equivalent dose H? 4. If you are in-charge to reduce this dose equivalent by 90%, at what distance from the source you recommend to this nuclear worker to stay?