Question

If a mineral has a daughter to parent ratio of 3:1 (three daughter atoms for every one parent atom), how many half lives have passed since the mineral formed

Answer 1

25% means has 2 halflives old.

The rock is 57 million years, which would be multiplied to 2(halflives) = 114 million years old.

Therefore, the halflives of the mineral formed is 2 and 1 halflife there is a total of 57 million years.