Answer:
The percentage rate of decay per year is of 3.25%.
The function showing the mass of the sample remaining after t is
Step-by-step explanation:
Equation for decay of substance:
The equation that models the amount of a decaying substance after t years is given by:
In which A(0) is the initial amount and r is the decay rate, as a decimal.
Every 21 years, its mass decreases by half.
This means that . We use this to find r, the percentage rate of decay per year.
The percentage rate of decay per year is of 3.25%.
Given that the initial mass of a sample of Element X is 80 grams.
This means that
The equation is:
The function showing the mass of the sample remaining after t is