Math 7 · Unit 2, Lesson 2: Part, Whole, and Percent · Tile 1 of 3
The Three Pieces
Whole, part, and percent
Every percent problem has three pieces. Today you find whichever one is missing.
Whole, part, percent
The whole is all of it: 100 percent. The part is some of it. The percent is what share the part is, out of 100. A class of 20 students is the whole. 5 of them wear glasses: that is the part. 5 out of 20 is 25 out of 100, so the percent is 25.
Every percent problem gives you two of the three and hides one. So the first question, every time, is: which piece is missing?
Every percent problem relates a part, a whole, and a percent.
Three pieces, one is missing. Figure out which one, and you know what to do.
The percent bar
One picture for the whole unit. Percents run along the bottom, from 0 to 100. Amounts run along the top, from 0 to the whole. Slide the percent and the bar shades that share and shows the matching amount. Here the whole is 20 students.
The bar is a double number line: every spot on it is a percent on the bottom and an amount on the top, and they always line up, because the relationship always multiplies by the same number.
Which piece is it?
Read each sentence and say what each number is: the whole, the part, or the percent. No solving yet. Just naming.
NC standards: NC.7.RP.3.