Question

There was a sample of 350 milligrams of a radioactive substance to start a study. since then, the sample has decayed by 7.3% each year. let t be the number of years since the start of the study. let y be the mass of the sample in milligrams. write an exponential function showing the relationship between y and t .

Answer 1

• y = 350*0.927^t

Explanation:

• Initial amount = 350 mg
• Decay = 7.3% per year or 0.073
• Time = t years
• Final mass = y

The equation:

• y = 350*(1 - 0.073)^t = 350*0.927^t