Radioactive substance

Question

If 8 grams of a radioactive substance are present initially and 8 years later only 4 grams remain, how much of the substance will be present after 16 years?

Round the final answer to three decimal places as needed. Round all intermediate values to seven decimal places as needed.

Answer 1

The half-life of the substance is 8 years. (No calculus needed!)

8 years after the 4 grams there shall be only 2 grams.