Three museums charge an entrance fee based on the number of visitors in the group. the table lists the fees charged by the museums. at which museum is the entrance fee proportional to the number of visitors? museum a museum b museum c visitors fee ($) visitors fee ($) visitors fee ($) 2 4 1 2 3 4 3 5 4 8 12 16 4 6 6 11 18 24

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.