30 Of What Number Is 90

30 of What Number is 90? Solving Percentage Problems

This article will guide you through solving the mathematical problem: "30 of what number is 90?" We'll break down the solution step-by-step, explain the underlying concepts, and offer practical applications for understanding percentages. This seemingly simple question touches upon fundamental mathematical principles used daily in various contexts, from calculating discounts to analyzing financial data.

Understanding the Problem:

The question "30 of what number is 90?" is essentially asking us to find the whole number when we know a part of it (30) and the percentage that part represents (a percentage that equates to 90). We can represent this mathematically using an equation.

Solving the Equation:

We can translate the problem into an algebraic equation:

30% * x = 90

Where 'x' represents the unknown number we're trying to find. To solve for x, we need to isolate it on one side of the equation. First, convert the percentage to a decimal by dividing by 100:

0.30 * x = 90

Now, divide both sides of the equation by 0.30:

x = 90 / 0.30

x = 300

Therefore, 30% of 300 is 90.

Alternative Method: Using Proportions:

Another way to solve this problem is by using proportions. We can set up a proportion like this:

30/100 = 90/x

This proportion states that 30 is to 100 (representing 30%) as 90 is to the unknown number (x). To solve for x, we can cross-multiply:

30 * x = 90 * 100

30x = 9000

x = 9000 / 30

x = 300

Again, we find that x = 300.

Practical Applications:

Understanding how to solve percentage problems like this has numerous real-world applications:

• Calculating Discounts: If a store offers a 30% discount on an item, and the discount amount is $90, you can use this method to determine the original price of the item.
• Analyzing Financial Statements: Understanding percentages is crucial for interpreting financial reports and understanding profit margins, growth rates, and other key financial metrics.
• Determining Grades: Many grading systems use percentages. If you scored 90 points on a test worth 30%, you could use this method to calculate the total points possible on the test.
• Everyday Percentage Calculations: From calculating tips to understanding sales tax, the ability to solve percentage problems is a valuable life skill.

Conclusion:

The answer to "30 of what number is 90?" is 300. By mastering these methods—using algebraic equations or proportions—you'll be equipped to solve a wide variety of percentage problems and apply this knowledge in various practical situations. Remember to always convert percentages to decimals before performing calculations for accurate results. Understanding these fundamentals is key to success in mathematics and its applications in everyday life.