We cаn extrаct the zircоns frоm these rоcks to obtаin an age of the zircons, thereby providing the age of the first preserved material on Earth.Within the zircons in this rock sample, the ratio of parent to daughter isotopes is 8.5:7.5 (parent:daughter). Using the chart below, determine how many half-lives have passed. Visual Description A graph illustrating the change in the number of radioactive isotopes over time as they decay. The horizontal axis is labeled “Number of half-lives”, ranging from 0 to 4. The vertical axis is labeled “Number of isotopes”, running from 0 to 16. Two smooth curves are shown: A green downward‑sloping curve represents the parent isotopes. It starts at the top left with a high number of parent atoms (around 16 at zero half-lives) and decreases steadily toward nearly zero by four half-lives.A blue upward‑sloping curve represents the daughter isotopes. It begins near zero at zero half-lives and rises to match the original parent amount by four half-lives. Both curves have black dots marking points along them. The green curve is labeled “Parent” near its lower right end, and the blue curve is labeled “Daughter” near its upper right portion.