Question

After three half-lives,what fraction of a radioactive sample remains.

Answer 1

after1 half life 50 percent
after another half life 50 percent of 50 percent which is 25 percent
after 3 half lifes 50 percent of 50 percent of 50 percent which is 50 percent of 25 which is 12.5 percent
12.5 percent is left