The expression used to calculate the percent remaining after half-lives is called what?

The expression used to calculate the percent remaining after half-lives is called what?

• A. Penetration
• B. Area measurement
• C. Percent remaining formula
• D. Half life

Answer: (C)

The key idea is how the amount left is calculated after a number of half-lives. Each half-life halves the quantity, so after n half-lives the remaining fraction is (1/2)^n, and the percent remaining is 100% × (1/2)^n. This is exactly what the “percent remaining formula” represents—the expression used to compute how much remains. The other terms don’t fit: penetration relates to how deeply radiation can pass through material, area measurement is about geometry, and a half-life is the time interval for the quantity to halve, not the calculation method itself.

The key idea is how the amount left is calculated after a number of half-lives. Each half-life halves the quantity, so after n half-lives the remaining fraction is (1/2)^n, and the percent remaining is 100% × (1/2)^n. This is exactly what the “percent remaining formula” represents—the expression used to compute how much remains. The other terms don’t fit: penetration relates to how deeply radiation can pass through material, area measurement is about geometry, and a half-life is the time interval for the quantity to halve, not the calculation method itself.