PSAT Math : Fractions and Percentage
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Example Questions
Example Question #161 : Fractions
If there are 3 boys in a class and 7 girls. What percent of the class is made up of boys?
25%
30%
70%
3%
30%
To solve this problem we set up a ratio of part of total. The part is the number of boys in the class and the total is the number of boys and girls in the class.
now to find the percent we can multiply this fraction by 10/10
From here we can see that it is 30%
Example Question #2 : How To Find Percentage From A Fraction
|
Marker Colors |
Students |
|
Blue |
13 |
|
Pink |
10 |
|
Orange |
5 |
|
Brown |
5 |
|
Green |
7 |
The above chart shows the number of students in a class who chose each of the five marker colors available.
What percentage of the class chose a green marker?
To figure out what percentage of the class chose green markers, you must first figure out what fraction of the class chose green markers. Then, you must convert that fraction into a percentage.
Figure out the fraction:
7 students chose green markers
40 students total
Fraction of students who chose green:
To convert this fraction to a percentage, you must multiply the fraction times 100, then divide the numerator by the denominator. You multiply the fraction times 100 because in order to figure out the percent, you must figure out what the fraction means "for (per) every hundred (cent)".
Multiply times 100
Therefore, the answer is 
Example Question #1 : How To Find A Fraction From A Percentage
Find the simplified fraction for
For any percent 
So we can write 
Then we simplify
So our simplified answer is
Example Question #171 : Arithmetic
You have 2 fair dice that each have 6 faces. On one roll, what's the probability that both dice land on an even number?
In order to find the probability of rolling two even numbers on 2 dice we need to find the probability of each dice having an even number on the roll and then multiply them together.
The probability of rolling an even number is
because 2, 4, and 6 are even numbers which goes in the numerator and there are 6 total numbers which goes in the denominator. After this we reduce the fraction and get one half. Then we need to muliply this by probability of the second dice having an even number.
Example Question #171 : Arithmetic
What is 15% of a $16.73 bill?
We can re write 15% as a fraction and then use proportions to solve.
From here we cross multiply and divide to solve for 
Example Question #2 : How To Find Fractional Percentages
If a test has a total of 
To solve this problem we set up a ratio. We want to find 
In the case 
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