PSAT Math : Fractions and Percentage

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : How To Find Percentage From A Fraction

If there are 3 boys in a class and 7 girls. What percent of the class is made up of boys?

Possible Answers:

70%

3%

25%

30%

Correct answer:

30%

Explanation:

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 #1731 : Psat Mathematics

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?

Possible Answers:

Correct answer:

Explanation:

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 #171 : Fractions

Find the simplified fraction for 

Possible Answers:

Correct answer:

Explanation:

For any percent  we can write it as a fraction in the form 

So we can write  as 

 

Then we simplify

So our simplified answer is 

Example Question #172 : Fractions

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?

Possible Answers:

Correct answer:

Explanation:

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 #1 : Fractions And Percentage

What is 15% of a $16.73 bill?

Possible Answers:

Correct answer:

Explanation:

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 #171 : Fractions

If a test has a total of  questions and  of the questions are multiple choice, how many questions are multiple choice?

Possible Answers:

Correct answer:

Explanation:

To solve this problem we set up a ratio. We want to find  of . Therefore, we set up the following ratio:

 

In the case  represents the number of questions that are multiple choice. From here we cross multiply and divide.

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