What is 30 Percent of 400? = 120 [With 2 Solutions]

Utilizing the “What is X Percent of Y Calculator”, we can compute that 30% of 400 equals 120.

Tips: Directly enter the numerical values. The calculator will automatically calculate the result.

Step-by-Step Solution: What is 30% of 400?

Now that we know we want to find 30% of 400, let’s look at two different step-by-step methods we can use to solve this percentage problem. Each approach arrives at the same solution, but understanding different ways to think through the math builds flexibility and deeper learning.

Method 1: Convert the Percent to a Decimal and Multiply

One approach to finding 30 percent of 400 is to convert the percent to a decimal and multiply. Here are the steps:

Step 1: Identify the part and whole

The part is the amount we want as a percentage. In this case, it is 30%.

The whole is the total amount. In this case, the whole is 400.

Step 2: Write the percentage as a decimal by dividing it by 100:

30% = 30/100 = 0.3

Step 3: Multiply the decimal form of percentage by the whole amount:

0.3 * 400 = 120

Therefore, 30% of 400 is 120.

Let’s look at this visually:

30% * 400 = 30/100 * 400 = 0.3 *400 = 120

This approach of converting the percentage to a decimal and multiplying is straightforward and can be applied to any “percent of number” problem. The key is properly converting the percent to a decimal by dividing by 100.

Method 2: Finding Percentages Using Algebraic Equations

Another way to find 30% of 400 is to set up an algebraic equation and solve it. Here are the steps:

A proportion is an equation that states two ratios are equivalent. Here is the proportion formula:

Part/Whole = Percentage/100

Step 1: Define the Unknown Variable

Let’s define an unknown variable x to represent 30% of 400. In algebraic equations, variables are used to represent unknown values.

Step 2: Set Up the Equation

Using the variable x, we can set up an equation with the information given:

• The unknown variable x (Part) is the amount we want to find, which is 30% of 400
• The Whole is 400
• The Percentage is 30

Substitute into the equation:

In this case, we can multiply both sides of the equation by 400

400 *x/400 = 30/100 * 400

x = 30 /100 * 400 = 12000/100 = 120

Therefore, 30% of 400 is 120.

Comparing the Methods

Both methods arrive at the same solution:

• Method 1 gets the solution by converting 30% to 0.3 and multiplying by 400.
• Method 2 sets up an equation, defines a variable, and solves algebraically.

The decimal conversion method is straightforward, avoiding any algebra. But the algebraic method is more flexible for complex problems where defining variables and setting up equations is helpful.

Common Percentage Scenarios

Here are some common percentage scenarios and how to solve them:

Finding the Percentage Given the Part and Whole

Here is the proportion formula:

Part/Whole = Percentage/100

We will now demonstrate how to utilize proportion formula to calculate the percentage given a part and whole amount through an example determining what percent of 400 is 120.

What Percent of 400 is 120?

Step 1: Define the Unknown Variable

Let unknown variable x = the unknown percent we want to find..

Step 2: Set Up the Equation

Using the variable x, we can set up an equation with the information given:.

• The unknown variable x (Percentage) is the number we want to find.
• The Part is 120
• The Whole is 400

Substitute into the equation:

120/400 = x/100

Step 3: Solve the Equation

To isolate x, we can cross multiply as follows:

• Take the numerator of one side of the equation, which is 120
• Multiply it by the denominator of the other side of the equation, which is 100
• Set that equal to the numerator of the second half (x) multiplied by the denominator of the first half (400)

When written out, the cross multiplication looks like:

120 * 100 = x * 400

x * 400 = 120 * 100

Then we can solve the resulting equation:

x * 400 = 12000

x = 30

Therefore, the answer is that 30% of 400 is 120.

Finding the Whole Given the Percentage and Part

Here is the proportion formula:

Part/Whole = Percentage/100

We will now demonstrate how to utilize proportion formula to calculate the whole given the percentage and part through an example determining 120 is 30 Percent of What Number.

120 is 30 Percent of What Number?

Step 1: Define the Unknown Variable

Let unknown variable x = the unknown number we want to find.

Step 2: Set Up the Equation

Using the variable x, we can set up an equation with the information given:

• The unknown variable x ( Whole) is the number we want to find.
• The Part is 120
• The Percentage is 30

Substitute into the equation:

120/x = 30/100

Step 3: Solve the Equation

To isolate x, we can cross multiply as follows:

• Take the numerator of one side of the equation, which is 120
• Multiply it by the denominator of the other side of the equation, which is 100
• Set that equal to the numerator of the second half (30) multiplied by the denominator of the first half (x)

When written out, the cross multiplication looks like:

120 * 100 = 30 * x

x * 30 = 120 * 100

Then we can solve the resulting equation:

x * 30 = 12000

x = 400

Therefore, the answer is that 120 is 30% of 400.

Common Percentage Calculations

Here is a quick reference table of some typical percentage calculations:

Calculation	Formula	Example
Find what percentage a part is of a whole	Part / Whole x 100%	120 / 400 x 100% = 30%
Find what percentage a part is of a whole	Part / Percentage	120 / 30% = 400
Find the part given the whole and percentage	Whole x Percentage	400 * 30% =120

Having these common formulas memorized can make solving a variety of percentage problems quicker. When in doubt, break things down step-by-step into smaller pieces.

Standard Percentage of 400 Calculation Examples

5 Percent of 400 = 5/100 * 400 = 0.05 * 400 = 20

10 Percent of 400 = 10/100 * 400 = 0.1 * 400 = 40

15 Percent of 400 = 15/100 * 400 = 0.15 * 400 = 60

20 Percent of 400 = 20/100 * 400 = 0.2 * 400 = 80

25 Percent of 400 = 25/100 * 400 = 0.25 * 400 = 100

30 Percent of 400 = 30/100 * 400 = 0.3 * 400 = 120

35 Percent of 400 = 35/100 * 400 = 0.35 * 400 = 140

40 Percent of 400 = 40/100 * 400 = 0.4 * 400 = 160

45 Percent of 400 = 45/100 * 400 = 0.45 * 400 = 180

50 Percent of 400 = 50/100 * 400 = 0.5 * 400 = 200

55 Percent of 400 = 55/100 * 400 = 0.55 * 400 = 220

60 Percent of 400 = 60/100 * 400 = 0.6 * 400 = 240

65 Percent of 400 = 65/100 * 400 = 0.65 * 400 = 260

70 Percent of 400 = 70/100 * 400 = 0.7 * 400 = 280

75 Percent of 400 = 75/100 * 400 = 0.75 * 400 = 300

80 Percent of 400 = 80/100 * 400 = 0.8 * 400 = 320

85 Percent of 400 = 85/100 * 400 = 0.85 * 120 = 340

90 Percent of 400 = 90/100 * 400 = 0.9 * 400 = 360

95 Percent of 400 = 95/100 * 400 = 0.95 * 400 = 380

100 Percent of 400 = 100/100 * 400 = 1 * 400 = 400