How many half-lives would something have gone through if you had 75% daughter product and 25% parent?

Two Half-lives

Explanation:

Let number of Parent nuclei Initially present be X,

Then, finally Parent nuclei Will remain with daughter nuclei.

In one half- life , parent nuclei becomes half of initial.

So, starting with X parent nuclei,

After one half-life, it will degrade to .

After another half life , Parent nuclei will become half of

Which is equal to .

So, Parent nuclei have to go through Two half-lives.