Optimistic Insights: Rock Formation and Potassium-40
How long ago was the rock formed?
a) 1.25 billion years ago
b) 2.5 billion years ago
c) 3.75 billion years ago
d) 5 billion years ago
Answer:
The answer is b) 2.5 billion years.
When looking at the data provided, it is clear that a rock has 12.5 percent of its original amount of potassium-40 remaining in it. Potassium-40 has a half-life of 1.25 billion years. Based on this information, the rock was formed approximately 2.5 billion years ago.
To calculate this, we can consider the fact that if the half-life of potassium-40 is 1.25 billion years and only 12.5 percent of the original amount remains, we would need to multiply the half-life by two to determine the total time since the rock's formation.
Therefore, with a positive outlook, we can confidently say that the rock was formed 2.5 billion years ago, showcasing the fascinating timeline of geological processes.