How to calculate percentages
Learn how to calculate percentages in this easy lesson! When you're asked to calculate an (unknown) percentage ("What percentage...?"), you need to first write the fraction PART/TOTAL, and then simply write that fraction as a decimal and as a percentage. See many examples below.
The concepts and ideas of this lesson are also explained in this video:
of the height of
a 15-ft tree is
a 3-ft sapling?
|A choir has 22 women and 18
men. Find what percentage
of the choir’s members are
|One pair of jeans costs $25 and another
costs $28. How many percent is the
price of cheaper jeans of the price of
the more expensive jeans?
Look carefully at the questions above. Notice that the problems don’t tell you the percentage; in other words, there is no number in the problem written as x%. Instead, they ask you to find it!
|Questions with “What percentage ... ?” or "How many percent ... ?"|
Asking “What percentage?” or "How many percent?" is the same as asking “How many hundredth parts?”
We can solve these questions in a two-part process:
1. First find out
the part that is being asked for as a
2. Convert that fraction to a decimal. Then
you can easily convert
Example 1. A choir has 22 women and 18 men. Find what percentage of the choir’s members are men.
1. Find out what
of the choir’s members are men.
2. Write 9/20 as a percent. Use
Example 2. One pair of jeans costs $25 and the other costs $28.
1. Write what part the
cheaper price is of the more expensive price.
2. Write 25/28 as a percentage. A
calculator gives 25/28 = 0.8928...
1. a. What percentage of a 15-ft tree is a little 3-ft sapling?
b. How many percent is $12 of $16?
2. Find how many percent the smaller object’s height is of the taller object’s height.
3. A 2-year old child measures 32
inches tall and weighs 24 pounds.
A 10-year old child measures 52 inches tall and weighs 96 pounds.
a. How many percent is the smaller child’s
age of the older child’s age?
b. How many percent is the smaller child’s
height of the older child’s height?
4. Write the percentages into the sectors in the circle graphs Think of fractions!
5. The circle graph at the right gives the angle measure
of each sector of the circle. Find what percentage each
sector is of the whole circle, and write the percentage
in the sector. Remember, the whole circle is 360°.
This lesson is taken from Maria Miller's book Math Mammoth Percent, and posted at www.HomeschoolMath.net with permission from the author. Copyright © Maria Miller.