SAT Math : How to find percentage from a fraction

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #11 : Percentage

What is  as a percentage?

Possible Answers:

Correct answer:

Explanation:

Convert the improper fraction  to the mixed numeral  or as the decimal .   as a percentage is

Example Question #12 : Percentage

A family with 6 children, aged 4, 4, 5, 7, 12, and 13 are moving to a new home. They all want the same bedroom, so the parents have a lottery. Each child places their name in once for every year of age (the four year olds each put their name in 4 times, the seven year old puts his name in 7 times, etc.) What is the probability of the chosen child being 4 years old?

Possible Answers:

None of the available answers

It is most likely that the chosen child will be the oldest child.

20\%

17.\overline{7}\%

8.\overline{8}\%

Correct answer:

17.\overline{7}\%

Explanation:

First, we will determine the total number of ballots:

4+4+5+7+12+13=45\hspace{1 mm}ballots

Since there are two four year olds, and this question is asking the probability of the chosen child being four, the probability is:

\frac{4+4}{45}=\frac{8}{45}=0.1\overline{7}=17.\overline{7}\%

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

Three hens each lay 20 eggs for a farmer. Two-fifths of the first hen's eggs are brown. One-fourth of the second hen's eggs are brown. Seven-tenths of the third hen's eggs are white. What percentage of all the eggs are brown?

Possible Answers:

Correct answer:

Explanation:

The first hen lays 8 brown eggs: 2/5 * 20 = 8

The second lays 5 brown eggs: 1/4 * 20 = 5

The third lays 6 brown eggs: 3/10 * 20 = 6

Add up the brown eggs and divide by 60, the total number of eggs:

19/60 = 0.31666667 = 31.67%, or 32%.

 

Example Question #21 : Percentage

What is the closest percent equal to the fraction ?

Possible Answers:

Correct answer:

Explanation:

The percent is a number over 100.  Set up the proportion to find the unknown value.

The closest answer is .

Example Question #21 : Percentage

Convert the following fraction to a percent, rounding to the nearest tenth:

Possible Answers:

Correct answer:

Explanation:

Reduce the fraction.

Set up the proportion such that some number is over 100.

Solve for , which is the percent.

Example Question #21 : Percentage

Express  as a percent. 

Possible Answers:

Correct answer:

Explanation:

To turn this fraction into a percent, let's write it as a decimal first. 

Now, let's set up a proportion to make this a percent.

Therefore, our answer is 

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