How old is the dinosaur fossil footprint based on the following information?
Consider the following scenario: I am a famous paleontologist and an expert in radioactive-dating techniques. I examine a dinosaur fossil footprint and discover that the fresh mud the dinosaur stepped in had just been covered with a thin layer of volcanic ash. I study the amount of potassium-40 and argon-40 in the ash. The ratio shows that 1/10 of one potassium-40 half-life has passed since the footprint was made. I know that the half-life of potassium-40 is 1.3 billion years.
