World population is increasing by 1.2% each year. In 2008, it was 6.68 billion. What will the population be in 2015?

Hello! For this question, we are compounding. The formula for compounding is P (1 + r) ^t, where P = initial amount, r = rate, and t = time in years. In this problem, the rate is 1.2%. 1.2% is 0.012 in decimal form. Let's add 1 to that. 1 + 0.012 is 1.012. That part is done. Next, we raise it to the 7th power, because 2008 to 2015 is 7 years apart. 1.012^7 is 1.08708521101. This is a long decimal, but do not delete it from your calculator. Now, we multiply that number by 6.68 billion, which is 6,680,000,000 in standard form. When you do that, you get 7,261,729,209.52 or 7,261,729,210 when rounded to the nearest whole number. There. The world population will be 7,261,729,210 by 2015.