Ariana starts with 100 milligrams of a radioactive substance. The amount of the substance decreases by 20% each week for a number of weeks, w. The expression 100(1 – 0.2)^w finds the amount of radioactive substance remaining after w weeks. Which statement about this expression is true?
It is the difference between the initial amount and the percent decrease.
It is the initial amount raised to the decay factor after w weeks.
It is the difference between the initial amount and the decay factor after w weeks.
It is the product of the initial amount and the decay factor after w weeks.