Percents
Can be represented as a decimal,
fraction, or with %
80% = .8 = 4/5
8% = .08 = 2/25
3
To represent 7 as a decimal, just
divide numerator by denominator
To find a percent of a number, we need to
make proportions.
part = %
whole 100
OR
Find 50% of 20.
What percent of 60 is 15?
440 is what percent of 400?
40 is 0.8% of what number?
is
of
= %
100
On the Hudson team of twenty four
students, two-thirds of the soccer team
can play goalie. On the Niagara Team,
37.5% of the thirty two students can play
goalie. Which team has more players that
can play goalie and by how many?
Percent Error
measured ‐ actual
actual
right ‐ wrong
right
I was buying my class pizza. I thought I would need 12 pies. Instead I only needed 10. By what percent was I wrong?
A student determined the density of zinc to be 6.63 g/cm3. The correct value is 7.13 g/cm3. Find the percent error in her measurement.
Sarah measures her rectangular bedroom window for a new shade. Her measurements are 36 inches by 42 inches. The actual measurements of the window are 36.5 inches and 42.5 inches.
Using the measurements that Sarah took, determine the number of square inches in the area of the window.
Determine the number of square inches in the actual area of the window.
Determine the relative error in calculating the area. Express your answer as a decimal to the nearest thousandth.
Percent Increase and Decrease
new ‐ original
original
From 25 to 49
From 14 to 98
From 50 to 45
From 10.5 to 9.9
From 300 to 30
30 is increased by 20%
2000 is increased by .02%
65 is decreased by 80%
40 is decreased by 15%
This week's price of gas of $2.80 a gallon. If there is going to be a 12% increase next week, what will be the price of a gallon of gasoline?
Jerid's parents presently pay $7,400 in school taxes. In next school year's budget there will be a 9.56% increase. What will Jerid's parents have to pay for school taxes next year?
A serving of Pete's Mint Chip Ice Cream Cookie has 1270 calories. A person needs between 2200 to 2500 calories for the entire day. What is the percent range of the caloric intake of a serving of Pete's Mint Chip Ice Cream Cookie? Express your answer to the nearest whole percent.
203 calories come from fat. What percent of the total calories from a serving of Pete's Mint Chip Ice Cream Cookie comes from fat?
A football player in the National football
League went from an average of 281 pounds in
1986 to 318 pounds in 2006. What is the
percent of increase, to the nearest tenth of a
percent, of a football player's weight for the
two decades?
When mixing a 12‐ounce can of lemonade mix with water is becomes 64 ounces of lemonade. If you serve an 8‐
ounce serving to each person, how many servings will you get out of one 12‐ounce can of lemonade mix? If you need 144 servings, how many 12‐ounce cans of lemonade mix will you need?