Question

The solar system started 4.6 billion years old. You are measuring the amount of calcium in the rock sample to determine if the rock was from the start of our solar system. Calcium has a half life of 1.25 billion years. The rock that you have found has experienced 3.6 half lives. QUESTION: is the rock likely a meteorite from the start of the solar system?

Answer 1

Half-life of a rock = 1.25 billion years

Rock lives of the rock found = 3.6 half-lives

Multiply the number of billion years of each half live (1.25) by the number of half-lives of the rock found:

1.25 x 3.6 = 4.5 billion years

Since the solar system started 4.6 billion years ago, the rock found is not from the start of the solar system.