Question

Dr. O'Keefe begins an experiment with 3 units of a radioactive material in his tank. Every day, half of the material in the tank will decompose. How many units of the material will he have left at the end of the 7th day?

Answer 1

3/128

Explanation:

3x(1/2)^7=3/128

Answer 2

3/128 or 0.023 units

Explanation:

Initial amount= 3 units

Rate of change= 1/2 times a day

Amount of material at the end of day 7= 3*(1/2)^7= 3/128 ≈ 0.023 units