What is the ratio of the number of the remaining atoms of X to that of Y after 200 years?

Two radioactive elements X and Y have half-lives of 100 and 50 years respectively. Samples of X and Y initially contain equal number of atoms. What is the ratio of the number of the remaining atoms of X to that of Y after 200 years?

A. 4:1
B. 3:1
C. 1:1
D. 1:2
E. 1:4

Correct Answer:

Option D – 1:2