7. (10 points) A single-story home with infiltration rate of 0.8 ach has 250 m² of floor space and a total volume of 500 m³. If 1 pCi/m²-s of radon

is emitted from the soil and enters the house, estimate the steady-state indoor radon concentration. Should this home take measures to lower the radon concentration, given that the action threshold is 4 pCi/L?The decay constant for radon is 7.6x10³ hr!.