Answer:
The age of the rock is years
Explanation:
We can write the formula for the quantity of material in an exponential decay as:
where is the initial quantity of the material, and is the mean lifetime of the material.
This means that the total material that has decayed is:
The mean lifetime can be obtained from the half-life ( ) by the relationship
For our problem, as there was no Sr-87 present in the rock initially, and its a product of the decay, its abundance will be given by , this means, the total quantity of material that has decayed.
So, our equation for the ratio will be
Working it a little
The half-life of the problem is
So, the age of the rock will be