Eric starts with 10 milligrams of a radioactive substance. the amount of the substance decreases by 12 each week for a number of weeks, w . he writes the expression 10(12) 10 ( 1 2 ) w to find the amount of radioactive substance remaining after w weeks. andrea starts with 1 1 milligram of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w . she writes the expression (1−0.2) 1 - 0 . 2 w to find the amount of radioactive substance remaining after w weeks. use the drop-down menus to explain what each part of eric’s and andrea’s expressions mean.

Mr. thompson is on a diet. he currently weighs 260 pounds. he loses 4 pounds per month. what part of the story makes the relationship not proportional?

Gabriel determined that his total cost would be represented by 2.5x + 2y – 2. his sister states that the expression should be x + x + 0.5x + y + y – 2. who is correct? explain.

In a study of the relationship between socio-economic class and unethical behavior, 129 university of california undergraduates at berkeley were asked to identify themselves as having low or high social-class by comparing themselves to others with the most (least) money, most (least) education, and most (least) respected jobs. they were also presented with a jar of individually wrapped candies and informed that the candies were for children in a nearby laboratory, but that they could take some if they wanted. after completing some unrelated tasks, participants reported the number of candies they had taken. it was found that those who were identiď¬ed as upper-class took more candy than others. in this study, identify: (a) the cases, (b) the variables and their types, (c) the main research question, (d) identify the population of interest and the sample in this study, and (e) comment on whether or not the results of the study can be generalized to the population, and if the ď¬ndings of the study can be used to establish causal relationships.