Play/run Gizmo for at least 40 seconds. It is fine if it runs past 40 seconds.
Click the table tab - at what time do you have exactly 1/2 radioactive atoms and 1/2 daughter atoms?
Redo and run the Gizmo with the settings two more times
Is the time exactly the same for all three trials?

Playrun Gizmo for at least 40 seconds It is fine if it runs past 40 seconds Click the table tab at what time do you have exactly 12 radioactive atoms and 12 dau class=