Algebra 1 : How to find percentage from a fraction

Study concepts, example questions & explanations for Algebra 1

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Example Questions

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

If Jessica got 2 out of 20 questions wrong on her most recent math quiz, what percent did she get correct? 

Possible Answers:

90%

20%

85%

80%

10%

Correct answer:

90%

Explanation:

Since she got 2 out of 20 incorrect, we can first figure out the percent incorrect. We can either find the decimal for 2/20, or make 2/20 a fraction with 100 in the denominator. In this case, it is simpler to do the latter. We need to multiply 20 by 5 to get 100, thus we multiply 2 by 5 to get 10. Then, we have that 2/20 is equivalent to 10/100. She lost 10 percent on her math quiz, leaving her with a score of 90%.

10/100 = 10% wrong

(100%) – (10% wrong) = 90% right

Example Question #2 : How To Find Percentage From A Fraction

Which of the following represents the fraction as a percentage?

Possible Answers:

80%

12.5%

8%

10.5%

18%

Correct answer:

12.5%

Explanation:

We need to set up a proportion to convert our fraction to x/100.

Cross multiply.

(1)(100) = (8)(x)

100 = 8x

Divide both sides by 8.

(100)/8 = (8x)/8

100/8 = x

Simplify.

100/8 = 25/2 = 12.5

Our answer is 12.5%.

Example Question #3 : How To Find Percentage From A Fraction

Possible Answers:

Correct answer:

Explanation:

Example Question #4 : How To Find Percentage From A Fraction

A die was rolled  times and landed on the number ""  times. What percent of the time was the result a number other than ?

Possible Answers:

Correct answer:

Explanation:

Here, the most important step is to understand what the question is asking.

A "" was rolled  of a total of  times, but the question is asking about numbers other than .

A number other than  was rolled  times of the total .

Now, the final step is to convert  into a percent. Since  is a multiple of , it is a quick conversion.  is equal to  and the answer is .

Example Question #5 : How To Find Percentage From A Fraction

Judy says she has  of her 8-page paper completed.  What percentage of the paper has she written?

Possible Answers:

Correct answer:

Explanation:

Use long division to divide out the fraction to determine the percentage:

Example Question #6 : How To Find Percentage From A Fraction

A very large bag is filled with marbles. of the bag is filled with red marbles. Another of the bag is filled with blue marbles. The rest of the bag is filled with yellow marbles. What percentage of the bag is filled with yellow marbles?

Possible Answers:

Correct answer:

Explanation:

First, you must find what fraction of the bag is filled with yellow marbles. We know that of the bag filled with red marbles and of the bag is filled with blue marbles. So, the fraction of the bag filled with yellow marbles must equal to

or

Next, you convert to a percentage, which is 25%.

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

Jamie ate of a pizza for lunch and of the same pizza later for dinner. What percentage of the pizza is left uneaten?

Possible Answers:

Correct answer:

Explanation:

Jamie ate of a pizza for lunch and of the same pizza for dinner. To convert a fraction to a percentage, you simply convert the fraction so that the denominator is 100. So, Jamie ate  of the pizza for lunch and  of the pizza for dinner. Since the denominator of these fractions is 100, the numerator is its percentage equivalent. Thus, Jamie ate 25% of the pizza for lunch and 20% for dinner for a total of 45% of the pizza. 55% of the pizza remains uneaten.

Example Question #8 : How To Find Percentage From A Fraction

Billy empties his pockets and finds some change. He finds 2 quarters, 4 dimes, 5 nickels and 9 pennies. What percentage of the coins are nickels?

Possible Answers:

25%

45%

10%

20%

35%

Correct answer:

25%

Explanation:

First, we can find out the proportion of coins that are nickels. So, we know there are 5 nickels and we can count there are 20 coins total

So there are  coins that are nickels. But the question asks for the percentage. To find the percentage, we can just find our answer as a decimal value rather than a fraction. Than multiply by 100%. So,

Thus our answer is 25%.

Example Question #9 : How To Find Percentage From A Fraction

A student took a test and got 13 out of 20 questions correct. What percentage of questions did this student get correct?

Possible Answers:

Correct answer:

Explanation:

We can mathematically write '13 out of 20' as a fraction.

We can convert this to a percent by setting up a proportion.

Cross multiply and solve for .

So, the student got of the questions correct.

 

Example Question #10 : How To Find Percentage From A Fraction

Write the following fraction as a percent

Possible Answers:

12.5%

51.2%

12%

25.1%

125%

Correct answer:

12.5%

Explanation:

To find the percent, first, set up the fraction as a long division problem where the 1 is placed inside the dividend and 8 is placed in the divisor:

Here, the decimal and the zero are included in the division.

Ignoring the decimal in the dividend and treating 1.0 equal to 10, we know that 8 divides into 10 one time.  Therefore, place that one on the top as shown below

Multiply that one by the divisor (8) to get eight (1 x 8 = 8) and then place that eight below the dividend as shown below

Subtract 8 from 10, which will give you 2. That 2 is placed at the bottom

To perform the division further, put in an additional zero in the dividend and another zero right beside the 2

This time, we have a 20 at the bottom. 8 can go into 20 two times so we place the two at the top of the (right next to 1) as shown

Multiply that two by 8 to get sixteen and place that sixteen at the bottom

Perform the usual subtraction to get 4

Place another zero inside the dividend and another zero right beside 4

This time 8 goes into 40 just perfectly (no remainder)

The decimal of the fraction  is 0.125.  To convert this to a percentage, move the decimal point two places to the right and then put in the '%' symbol so that 0.125 is written as 12.5%

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