A space probe is powered by a Radioisotope Thermoelectric Generator (RTG). The thermal power output of the RTG is directly proportional to the activity of its Plutonium-238 source.
At launch, the thermal power output of the RTG is 800 W800\text{ W}800 W.
After 10 years10\text{ years}10 years in space, the thermal power output has decreased to 720 W720\text{ W}720 W.
What will the thermal power output of the RTG be 30 years30\text{ years}30 years after launch?
560 W560\text{ W}560 W
583 W583\text{ W}583 W
640 W640\text{ W}640 W
729 W729\text{ W}729 W
