Assume someone had $100,000 in their retirement account on 3/3/2013. The five-year rate of 3.98% means that each year their initial balance will grow by 3.98%. To find out how much money they will have in their account five years later, we can fill in the following table:
Five Year Rate: 3.98%
Date
Initial Principal
Interest
Ending Principal
3/31/2013
3/31/2014
3/31/2015
3/31/2016
3/31/2017
3/31/2018
Guided Practice Activity #3 - Parts of the Pop
The most common interpretation of a percentage is as a part-to-whole ratio. Indeed, many people define percentages as part-to-whole ratios, which can cause much confusion when dealing with other uses of percentages. If we are given the ratio of boys to girls in a class is 2:3, then it can be easy to mistakenly say, "The boys are 66.7% of the class," or even worse, "66.7% of the girls are boys!" The correct statement uses the size of each part: "The number of boys is 66.7% of the number of girls."
Boys (part)
Girls (part)
Students (whole)
2
3
5
66.7
100
40
60
100
We can add the parts to get the whole: 2 boys : 3 girls : 5 students. And then scaling the whole to 100, we get 40 boys, 60 girls, 100 students. So the boys are 40% of the class, not 66.7%. To summarize, we use each of the numbers in the first column in a sentence.