Common Core: 6th Grade Math : Find a Percent of a Quantity as a Rate Per 100: CCSS.Math.Content.6.RP.A.3c

Study concepts, example questions & explanations for Common Core: 6th Grade Math

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Example Questions

Example Question #732 : Ssat Middle Level Quantitative (Math)

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 100\) cars in the parking lot and \(\displaystyle 60 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 56\)

\(\displaystyle 72\)

\(\displaystyle 60\)

\(\displaystyle 64\)

\(\displaystyle 36\)

Correct answer:

\(\displaystyle 60\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 60\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 60\) of them are red. We can write the following ratio:

\(\displaystyle 60:100\rightarrow\frac{60}{100}\)

Reduce.

\(\displaystyle \frac{60}{100}\rightarrow \frac{6}{10}\rightarrow \frac{3}{5}\)

We know that there are \(\displaystyle 100\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:100\rightarrow \frac{Red}{100}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{3}{5}=\frac{Red}{100}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 5 \times Red=3\times100\)

Simplify.

\(\displaystyle 5 Red=300\)

Divide both sides of the equation by \(\displaystyle 5\).

\(\displaystyle \frac{5Red}{5}=\frac{300}{5}\)

Solve.

\(\displaystyle Red=60\)

There are \(\displaystyle 60\) red cars in the parking lot.

 

Example Question #241 : Numbers And Operations

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 250\) cars in the parking lot and \(\displaystyle 10 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 30\)

\(\displaystyle 52\)

\(\displaystyle 50\)

\(\displaystyle 25\)

\(\displaystyle 15\)

Correct answer:

\(\displaystyle 25\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 10\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 10\) of them are red. We can write the following ratio:

\(\displaystyle 10:100\rightarrow\frac{10}{100}\)

Reduce.

\(\displaystyle \frac{10}{100}\rightarrow \frac{1}{10}\)

We know that there are \(\displaystyle 250\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:250\rightarrow \frac{Red}{250}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{1}{10}=\frac{Red}{250}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 10 \times Red=1\times 250\)

Simplify.

\(\displaystyle 10 Red=250\)

Divide both sides of the equation by \(\displaystyle 10\).

\(\displaystyle \frac{10Red}{10}=\frac{250}{10}\)

Solve.

\(\displaystyle Red=25\)

There are \(\displaystyle 25\) red cars in the parking lot.

Example Question #242 : Numbers And Operations

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 136\) cars in the parking lot and \(\displaystyle 25 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 54\)

\(\displaystyle 34\)

\(\displaystyle 45\)

\(\displaystyle 38\)

\(\displaystyle 43\)

Correct answer:

\(\displaystyle 34\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 25\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 25\) of them are red. We can write the following ratio:

\(\displaystyle 25:100\rightarrow\frac{25}{100}\)

Reduce.

\(\displaystyle \frac{25}{100}\rightarrow \frac{1}{4}\)

We know that there are \(\displaystyle 136\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:136\rightarrow \frac{Red}{136}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{1}{4}=\frac{Red}{136}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 4 \times Red=1\times136\)

Simplify.

\(\displaystyle 4 Red=136\)

Divide both sides of the equation by \(\displaystyle 4\).

\(\displaystyle \frac{4Red}{4}=\frac{136}{4}\)

Solve.

\(\displaystyle Red=34\)

There are \(\displaystyle 34\) red cars in the parking lot.

Example Question #741 : Ssat Middle Level Quantitative (Math)

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 164\) cars in the parking lot and \(\displaystyle 25 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 47\)

\(\displaystyle 41\)

\(\displaystyle 52\)

\(\displaystyle 33\)

\(\displaystyle 36\)

Correct answer:

\(\displaystyle 41\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 25\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 25\) of them are red. We can write the following ratio:

\(\displaystyle 25:100\rightarrow\frac{25}{100}\)

Reduce.

\(\displaystyle \frac{25}{100}\rightarrow \frac{1}{4}\)

We know that there are \(\displaystyle 164\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:164\rightarrow \frac{Red}{164}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{1}{4}=\frac{Red}{164}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 4 \times Red=1\times164\)

Simplify.

\(\displaystyle 4 Red=164\)

Divide both sides of the equation by \(\displaystyle 4\).

\(\displaystyle \frac{4Red}{4}=\frac{164}{4}\)

Solve.

\(\displaystyle Red=41\)

There are \(\displaystyle 41\) red cars in the parking lot.

Example Question #21 : Percentage

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 135\) cars in the parking lot and \(\displaystyle 60 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 93\)

\(\displaystyle 72\)

\(\displaystyle 81\)

\(\displaystyle 79\)

\(\displaystyle 60\)

Correct answer:

\(\displaystyle 81\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 60\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 60\) of them are red. We can write the following ratio:

\(\displaystyle 60:100\rightarrow\frac{60}{100}\)

Reduce.

\(\displaystyle \frac{60}{100}\rightarrow \frac{6}{10}\rightarrow \frac{3}{5}\)

We know that there are \(\displaystyle 135\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:135\rightarrow \frac{Red}{135}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{3}{5}=\frac{Red}{135}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 5 \times Red=3\times135\)

Simplify.

\(\displaystyle 5 Red=405\)

Divide both sides of the equation by \(\displaystyle 5\).

\(\displaystyle \frac{5Red}{5}=\frac{405}{5}\)

Solve.

\(\displaystyle Red=81\)

There are \(\displaystyle 81\) red cars in the parking lot.

Example Question #243 : Numbers And Operations

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 400\) cars in the parking lot and \(\displaystyle 40 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 148\)

\(\displaystyle 61\)

\(\displaystyle 160\)

\(\displaystyle 164\)

\(\displaystyle 116\)

Correct answer:

\(\displaystyle 160\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 40\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 40\) of them are red. We can write the following ratio:

\(\displaystyle 40:100\rightarrow\frac{40}{100}\)

Reduce.

\(\displaystyle \frac{40}{100}\rightarrow \frac{4}{10}\rightarrow \frac{2}{5}\)

We know that there are \(\displaystyle 400\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:400\rightarrow \frac{Red}{400}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{2}{5}=\frac{Red}{400}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 5 \times Red=2\times400\)

Simplify.

\(\displaystyle 5 Red=800\)

Divide both sides of the equation by \(\displaystyle 5\).

\(\displaystyle \frac{5Red}{5}=\frac{800}{5}\)

Solve.

\(\displaystyle Red=160\)

There are \(\displaystyle 160\) red cars in the parking lot.

Example Question #22 : Percentage

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 200\) cars in the parking lot and \(\displaystyle 50 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 102\)

\(\displaystyle 210\)

\(\displaystyle 100\)

\(\displaystyle 120\)

\(\displaystyle 120\)

Correct answer:

\(\displaystyle 100\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 50\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 50\) of them are red. We can write the following ratio:

\(\displaystyle 50:100\rightarrow\frac{50}{100}\)

Reduce.

\(\displaystyle \frac{50}{100}\rightarrow \frac{5}{10}\rightarrow \frac{1}{2}\)

We know that there are \(\displaystyle 200\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:200\rightarrow \frac{Red}{200}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{1}{2}=\frac{Red}{200}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 2 \times Red=1\times200\)

Simplify.

\(\displaystyle 2 Red=200\)

Divide both sides of the equation by \(\displaystyle 2\).

\(\displaystyle \frac{2Red}{2}=\frac{200}{2}\)

Solve.

\(\displaystyle Red=100\)

There are \(\displaystyle 100\) red cars in the parking lot.

Example Question #85 : Numbers And Operations

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 300\) cars in the parking lot and \(\displaystyle 30 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 99\)

\(\displaystyle 90\)

\(\displaystyle 72\)

\(\displaystyle 81\)

\(\displaystyle 74\)

Correct answer:

\(\displaystyle 90\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 30\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 30\) of them are red. We can write the following ratio:

\(\displaystyle 30:100\rightarrow\frac{30}{100}\)

Reduce.

\(\displaystyle \frac{30}{100}\rightarrow \frac{3}{10}\)

We know that there are \(\displaystyle 300\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:300\rightarrow \frac{Red}{300}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{3}{10}=\frac{Red}{300}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 10 \times Red=3\times300\)

Simplify.

\(\displaystyle 10 Red=900\)

Divide both sides of the equation by \(\displaystyle 10\).

\(\displaystyle \frac{10Red}{10}=\frac{900}{10}\)

Solve.

\(\displaystyle Red=90\)

There are \(\displaystyle 90\) red cars in the parking lot.

Example Question #1 : Find A Percent Of A Quantity As A Rate Per 100: Ccss.Math.Content.6.Rp.A.3c

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 400\) cars in the parking lot and \(\displaystyle 4 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 36\)

\(\displaystyle 8\)

\(\displaystyle 24\)

\(\displaystyle 16\)

\(\displaystyle 18\)

Correct answer:

\(\displaystyle 16\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 4\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 4\) of them are red. We can write the following ratio:

\(\displaystyle 4:100\rightarrow\frac{4}{100}\)

Reduce.

\(\displaystyle \frac{4}{100}\rightarrow \frac{2}{50}\rightarrow \frac{1}{25}\)

We know that there are \(\displaystyle 400\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:40\rightarrow \frac{Red}{400}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{1}{25}=\frac{Red}{400}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 25 \times Red=1\times400\)

Simplify.

\(\displaystyle 25 Red=400\)

Divide both sides of the equation by \(\displaystyle 25\).

\(\displaystyle \frac{25Red}{25}=\frac{400}{25}\)

Solve.

\(\displaystyle Red=16\)

There are \(\displaystyle 16\) red cars in the parking lot.

Example Question #64 : Grade 6

Red is a very popular car color. A production company manufactures cars and parks them in a lot behind the plant. There are \(\displaystyle 200\) cars in the parking lot and \(\displaystyle 35 \%\) of them are red. How many red cars are in the parking lot?

Possible Answers:

\(\displaystyle 72\)

\(\displaystyle 70\)

\(\displaystyle 35\)

\(\displaystyle 80\)

\(\displaystyle 89\)

Correct answer:

\(\displaystyle 70\)

Explanation:

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that \(\displaystyle 35\%\) of the cars are red. In other words, for every hundred cars \(\displaystyle 35\) of them are red. We can write the following ratio:

\(\displaystyle 35:100\rightarrow\frac{35}{100}\)

Reduce.

\(\displaystyle \frac{35}{100}\rightarrow \frac{7}{20}\)

We know that there are \(\displaystyle 200\) cars in the parking lot. We can write the following ratio by substituting the variable \(\displaystyle Red\) for the number of red cars:

\(\displaystyle Red:200\rightarrow \frac{Red}{200}\)

Now, we can create a proportion using our two ratios.

\(\displaystyle \frac{7}{20}=\frac{Red}{200}\)

Cross multiply and solve for \(\displaystyle Red\).

\(\displaystyle 20 \times Red=7\times200\)

Simplify.

\(\displaystyle 20Red=1400\)

Divide both sides of the equation by \(\displaystyle 5\).

\(\displaystyle \frac{20Red}{20}=\frac{1400}{20}\)

Solve.

\(\displaystyle Red=70\)

There are \(\displaystyle 70\) red cars in the parking lot.

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