What is the formula?
Percent Equation
Part = Percent x Whole
20% markup
1.2
2 years
2
10 is what percent of 50?
Percent
20% of 30
6
Percent Proportion
Part / Whole = Percent / 100
25% discount
0.75
3 months
1/4 or 0.25
15 is 20% of what number?
Whole
90 is 50% of what number?
180
Percent of Change
Percent of change = Amt. of change / Orig. amt.
1.07
5 and one half years
5.5
What number is 30% of 100?
Part
Last year, the 7th grade class had 16 students. This year, the 7th grade class has 20 students. What is the percent of change in the number of students from last year to this year?
25% increase.
Percent Error
Percent error = Amt. of error / actual amt.
9% sales tax with a 15% tip
1.24
40 months
3 1/3 or 3.33
20 / x = 50 / 100
Whole
On a certain day, a random math teacher guessed that 18 students would be present to take their math test. Miraculously, all 20 students were present to take the test! What was the percent error for the math teacher's prediction?
10%
Simple Interest
I = prt
10% tax on a 50% discount
0.55
730 days
2
An ECA bake sale brought in a total of $1.200.000 pesos last month. This month, the bake sale brought in 90% as much as last month. How much money did the bake sale bring in this month?
Part
At the end of a math teacher's time of teaching a class, his students were so thankful for the many, many, many, many things that he had taught them that they insisted on taking him to dinner! The bill was $700.000 pesos, which thankfully included taxes, but not a tip. They agreed to leave a 15% tip for the excellent service. What was their total payment?
$805.000 pesos