According to the 2005-2009 Community Service Survey, the racial and ethnic composition of Los Angeles, California is as follows: White (41.3%), Latino/Hispanic (29.4%), Asian (10.7%) and African-American (9.8%). However, in Little Tokyo, Asians comprise 48% of the population, followed by Whites (18%), African Americans (18%), and Latinos (16%). This difference demonstrates why it is important for geographers to study the of population distributions.

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.