A Rock Contains 0 $\text { half-life }$ For the Decay of Uranium-238 to Lead-206 Is 4

A rock contains 0.413 mg of lead-206 for each milligram of uranium-238.The $\text { half-life }$ for the decay of uranium-238 to lead-206 is 4.5 × 10⁹ y.The rock was formed ________ y.ago.

A) 4.80 × 10⁹
B) 1.86 × 10⁹
C) 3.10 × 10⁹
D) 7.34 × 10⁹
E) 2.53 × 10⁹