There are 12 students running for three student coun- cil positions: president, vice president, and secretary.
Which of the following expressions represents the
number of ways in which these three positions can be
filled by the 12 candidates?
(a) 12.12.12
(c) 12.11.10
3.2.1
(b) 12 · 11 · 10
(d) 12!

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.