Kelly took a quiz on decimals that had 151515 questions. she got \dfrac45
5
4
start fraction, 4, divided by, 5, end fraction of those questions correct.
she took another quiz on fractions that had 121212 questions. she got \dfrac56
6
5
start fraction, 5, divided by, 6, end fraction of those questions correct.

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? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.