Strip diagrams (or percent bars) play a pivotal role in demonstrating the relationship of the percent to the part and whole.
This conceptual understanding helps your visual learners especially and will also show students how you can use benchmark percents (25%, 50%, and 75%) to estimate the answer.
We begin by subtracting the smaller number (the old value) from the greater number (the new value) to find the amount of change.
$$240-150=90$$ Then we find out how many percent this change corresponds to when compared to the original number of students $$a=r\cdot b$$ $$90=r\cdot 150$$ $$\frac=r$$ $$0.6=r= 60\%$$ We begin by finding the ratio between the old value (the original value) and the new value $$percent\:of\:change=\frac=\frac=1.6$$ As you might remember 100% = 1.
You will be given two of the values, or at least enough information that you can figure two of them out.
Then you'll need to pick a variable for the value you don't have, write an equation, and solve for that variable.
In the above example, I first had to figure out what the actual tax was.
Many percentage problems are really "two-part-ers" like this: they involve some kind of increase or decrease relative to some original value.
Warning: Always figure the percentage of change relative to the Standardized Test Prep ACCUPLACER Math ACT Math ASVAB Math CBEST Math CHSPE Math CLEP Math COMPASS Math FTCE Math GED Math GMAT Math GRE Math MTEL Math NES Math PERT Math PRAXIS Math SAT Math TABE Math TEAS Math TSI Math more tests...
To solve problems with percent we use the percent proportion shown in "Proportions and percent".