Question

A sample of a material has 200 radioactive particles in it today. Your great-grandmother measured 400 radioactive particles in it 100 years ago. 100 years from today, how many radioactive particles will the sample have?

Answer 1

It will have 100 radioactive particles.

Answer 2

100 Radioactive particles

Step-by-step explanation:

If your great-grandmother measured 400 radioactive particles 100 years ago and today it has 200 radioactive particles, we observe that the half-life of this particles is 100 year.

That means that each 100 years the number of radioactive particles drop to half of it's original number.

400 radioactive particles--100 year--200 radioactive particles --100 years-- 100 radioactive particles