Question

If a rock contains 75% of the decay product, how many half lives have passed

Answer 1

Approximately 0.415 half-lives have passed.

Step-by-step explanation:

If a rock contains 75% of the decay product, we can determine the number of half-lives that have passed by using the equation:

Number of half-lives = log2(0.75)

We can use logarithms to solve this equation. Taking the logarithm of 0.75 to the base 2 gives:

log2(0.75) ≈ -0.415

Since half-lives cannot be negative, we take the absolute value of the result:

Number of half-lives ≈ 0.415

Therefore, approximately 0.415 half-lives have passed.

Answer 2

Answer: After one half-life has passed, half (50%, or four) of the parent atoms in each mineral grain have been transformed into their daughter products (red squares). After two half-lives have passed, 75% (six) of the original parent atoms in each grain have been transformed into daughter products.