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

1

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$8:100\rightarrow\frac{8}{100}$

Reduce.

$\frac{8}{100}\rightarrow \frac{4}{50}\rightarrow \frac{2}{25}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:3200\rightarrow \frac{Red}{3200}$

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

$\frac{2}{25}=\frac{Red}{3200}$

Cross multiply and solve for .

$25 \times Red=2\times3200$

Simplify.

Divide both sides of the equation by .

$\frac{25Red}{25}=\frac{6400}{25}$

Solve.

There are red cars in the parking lot.

2

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$25:100\rightarrow\frac{25}{100}$

Reduce.

$\frac{25}{100}\rightarrow \frac{1}{4}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:136\rightarrow \frac{Red}{136}$

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

$\frac{1}{4}=\frac{Red}{136}$

Cross multiply and solve for .

$4 \times Red=1\times136$

Simplify.

Divide both sides of the equation by .

$\frac{4Red}{4}=\frac{136}{4}$

Solve.

There are red cars in the parking lot.

3

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$4:100\rightarrow\frac{4}{100}$

Reduce.

$\frac{4}{100}\rightarrow \frac{2}{50}\rightarrow \frac{1}{25}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:40\rightarrow \frac{Red}{400}$

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

$\frac{1}{25}=\frac{Red}{400}$

Cross multiply and solve for .

$25 \times Red=1\times400$

Simplify.

Divide both sides of the equation by .

$\frac{25Red}{25}=\frac{400}{25}$

Solve.

There are red cars in the parking lot.

4

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$40:100\rightarrow\frac{40}{100}$

Reduce.

$\frac{40}{100}\rightarrow \frac{4}{10}\rightarrow \frac{2}{5}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:400\rightarrow \frac{Red}{400}$

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

$\frac{2}{5}=\frac{Red}{400}$

Cross multiply and solve for .

$5 \times Red=2\times400$

Simplify.

Divide both sides of the equation by .

$\frac{5Red}{5}=\frac{800}{5}$

Solve.

There are red cars in the parking lot.

5

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$30:100\rightarrow\frac{30}{100}$

Reduce.

$\frac{30}{100}\rightarrow \frac{3}{10}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:300\rightarrow \frac{Red}{300}$

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

$\frac{3}{10}=\frac{Red}{300}$

Cross multiply and solve for .

$10 \times Red=3\times300$

Simplify.

Divide both sides of the equation by .

$\frac{10Red}{10}=\frac{900}{10}$

Solve.

There are red cars in the parking lot.

6

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$60:100\rightarrow\frac{60}{100}$

Reduce.

$\frac{60}{100}\rightarrow \frac{6}{10}\rightarrow \frac{3}{5}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:100\rightarrow \frac{Red}{100}$

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

$\frac{3}{5}=\frac{Red}{100}$

Cross multiply and solve for .

$5 \times Red=3\times100$

Simplify.

Divide both sides of the equation by .

$\frac{5Red}{5}=\frac{300}{5}$

Solve.

There are red cars in the parking lot.

7

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$60:100\rightarrow\frac{60}{100}$

Reduce.

$\frac{60}{100}\rightarrow \frac{6}{10}\rightarrow \frac{3}{5}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:135\rightarrow \frac{Red}{135}$

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

$\frac{3}{5}=\frac{Red}{135}$

Cross multiply and solve for .

$5 \times Red=3\times135$

Simplify.

Divide both sides of the equation by .

$\frac{5Red}{5}=\frac{405}{5}$

Solve.

There are red cars in the parking lot.

8

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$35:100\rightarrow\frac{35}{100}$

Reduce.

$\frac{35}{100}\rightarrow \frac{7}{20}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:200\rightarrow \frac{Red}{200}$

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

$\frac{7}{20}=\frac{Red}{200}$

Cross multiply and solve for .

$20 \times Red=7\times200$

Simplify.

Divide both sides of the equation by .

$\frac{20Red}{20}=\frac{1400}{20}$

Solve.

There are red cars in the parking lot.

9

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio:

$80:100\rightarrow\frac{80}{100}$

Reduce.

$\frac{80}{100}\rightarrow \frac{8}{10}\rightarrow \frac{4}{5}$

We know that there are cars in the parking lot. We can write the following ratio by substituting the variable for the number of red cars:

$Red:800\rightarrow \frac{Red}{800}$

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

$\frac{4}{5}=\frac{Red}{800}$

Cross multiply and solve for .

$5 \times Red=4\times800$

Simplify.

Divide both sides of the equation by .

$\frac{5Red}{5}=\frac{3200}{5}$

Solve.

There are red cars in the parking lot.

10

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

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 of the cars are red. In other words, for every hundred cars of them are red. We can write the following ratio: