A radioisotope has a half-life of 900 seconds. Calculate the fraction of the original isotope which will remain behind after four half-life periods.

Explanation

To solve the problem of calculating the fraction of a radioisotope that remains after four half-lives, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Half-Life Concept**: The half-life of a substance is the time required for half of the substance to decay. In this case, the half-life of the radioisotope is given as 900 seconds.

2. **Determine the Number of Half-Lives**: We need to find out how much of the radioisotope remains after four half-lives. Since each half-life is 900 seconds, four half-lives will be:
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