Inverse Proportion Practice Problems and Solutions

Master inverse proportionality with step-by-step practice problems. Learn to identify inverse relationships, solve equations, and apply concepts to real-world scenarios.

📚What You'll Master in This Practice Session
  • Identify inverse proportional relationships from tables and real-world examples
  • Apply the inverse proportion function Y = a/X to solve problems
  • Calculate how variables change when one increases and another decreases proportionally
  • Verify inverse proportionality by checking multiplication and division patterns
  • Solve practical problems involving speed, time, distance, and resource consumption
  • Graph inverse proportion relationships and interpret their hyperbolic curves

Understanding Inverse Proportion

Complete explanation with examples

Inverse Proportion

Inverse proportionality describes a situation in which, when one term is multiplied by a certain number of times, the second term is decreased by the same number of times. This also occurs in reverse, if one term decreases by a certain number of times, the second term increases by the same number of times.

Let's see an example to illustrate this concept.

Given the following table:

We see two values, X X and Y Y . It can be very clearly seen that, when the value of X X increases by 2 2 , the value of Y Y also decreases 2 2 times. Therefore, it can be said that there is inverse proportionality here.

Inverse Proportion

Detailed explanation

Practice Inverse Proportion

Test your knowledge with 3 quizzes

How many times longer is the radius of the red circle than the radius of the blue circle?

210

Examples with solutions for Inverse Proportion

Step-by-step solutions included
Exercise #1

If there are 18 balls in a box of which 23 \frac{2}{3} are white:

How many white balls are there in the box in total?

Step-by-Step Solution

To solve this problem, we will determine the number of white balls in the box using a fraction of the total number of balls.

We are given the total number of balls in the box as 18, and we know that 23 \frac{2}{3} of these balls are white. To find the number of white balls, we follow these steps:

  • Step 1: Identify the total quantity, which is 18 balls.
  • Step 2: Use the given fraction 23 \frac{2}{3} to find the number of white balls.
  • Step 3: Multiply the total number of balls by the fraction of white balls: 18×23 18 \times \frac{2}{3} .

Perform the calculation:

18×23=18×0.6667=12 18 \times \frac{2}{3} = 18 \times 0.6667 = 12

Alternatively, calculate directly using fractions:

18×23=18×23=363=12 18 \times \frac{2}{3} = \frac{18 \times 2}{3} = \frac{36}{3} = 12

Thus, the total number of white balls in the box is 12.

Therefore, the correct answer is choice 12.

Answer:

12

Video Solution
Exercise #2

In a box there are 28 balls, 14 \frac{1}{4} of which are orange.

How many orange balls are there in the box in total?

Step-by-Step Solution

To solve this problem, we'll determine the number of orange balls by calculating the fraction of the total number of balls:

  • Step 1: Identify the total number of balls, 28 28 .
  • Step 2: Note the fraction representing the orange balls, 14 \frac{1}{4} .
  • Step 3: Apply the formula to find the number of orange balls:
    Number of orange balls =28×14 = 28 \times \frac{1}{4}

Now, let's perform the calculation:
28×14=28÷4=7 28 \times \frac{1}{4} = 28 \div 4 = 7

Therefore, the number of orange balls in the box is 7 7 .

Answer:

7

Video Solution
Exercise #3

There are two circles.

One circle has a radius of 4 cm, while the other circle has a radius of 10 cm.

How many times greater is the area of the second circle than the area of the first circle?

Step-by-Step Solution

The area of a circle is calculated using the following formula:

where r represents the radius.

Using the formula, we calculate the areas of the circles:

Circle 1:

π*4² =

π16

Circle 2:

π*10² =

π100

To calculate how much larger one circle is than the other (in other words - what is the ratio between them)

All we need to do is divide one area by the other.

100/16 =

6.25

Therefore the answer is 6 and a quarter!

Answer:

614 6\frac{1}{4}

Video Solution
Exercise #4

The rectangle ABCD is shown below.

AB = X

The ratio between AB and BC is x2 \sqrt{\frac{x}{2}} .


The length of diagonal AC is labelled m.

XXXmmmAAABBBCCCDDD

Determine the value of m:

Step-by-Step Solution

We know that:

ABBC=x2 \frac{AB}{BC}=\sqrt{\frac{x}{2}}

We also know that AB equals X.

First, we will substitute the given data into the formula accordingly:

xBC=x2 \frac{x}{BC}=\frac{\sqrt{x}}{\sqrt{2}}

x2=BCx x\sqrt{2}=BC\sqrt{x}

x2x=BC \frac{x\sqrt{2}}{\sqrt{x}}=BC

x×x×2x=BC \frac{\sqrt{x}\times\sqrt{x}\times\sqrt{2}}{\sqrt{x}}=BC

x×2=BC \sqrt{x}\times\sqrt{2}=BC

Now let's look at triangle ABC and use the Pythagorean theorem:

AB2+BC2=AC2 AB^2+BC^2=AC^2

We substitute in our known values:

x2+(x×2)2=m2 x^2+(\sqrt{x}\times\sqrt{2})^2=m^2

x2+x×2=m2 x^2+x\times2=m^2

Finally, we will add 1 to both sides:

x2+2x+1=m2+1 x^2+2x+1=m^2+1

(x+1)2=m2+1 (x+1)^2=m^2+1

Answer:

m2+1=(x+1)2 m^2+1=(x+1)^2

Video Solution
Exercise #5

Given the rectangle ABCD

AB=X the ratio between AB and BC is equal tox2 \sqrt{\frac{x}{2}}

We mark the length of the diagonal A A with m m

Check the correct argument:

XXXmmmAAABBBCCCDDD

Step-by-Step Solution

Let's find side BC

Based on what we're given:

ABBC=xBC=x2 \frac{AB}{BC}=\frac{x}{BC}=\sqrt{\frac{x}{2}}

xBC=x2 \frac{x}{BC}=\frac{\sqrt{x}}{\sqrt{2}}

2x=xBC \sqrt{2}x=\sqrt{x}BC

Let's divide by square root x:

2×xx=BC \frac{\sqrt{2}\times x}{\sqrt{x}}=BC

2×x×xx=BC \frac{\sqrt{2}\times\sqrt{x}\times\sqrt{x}}{\sqrt{x}}=BC

Let's reduce the numerator and denominator by square root x:

2x=BC \sqrt{2}\sqrt{x}=BC

We'll use the Pythagorean theorem to calculate the area of triangle ABC:

AB2+BC2=AC2 AB^2+BC^2=AC^2

Let's substitute what we're given:

x2+(2x)2=m2 x^2+(\sqrt{2}\sqrt{x})^2=m^2

x2+2x=m2 x^2+2x=m^2

Answer:

x2+2x=m2 x^2+2x=m^2

Video Solution

Frequently Asked Questions

What is inverse proportion and how do I recognize it?

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Inverse proportion occurs when one variable increases while another decreases by the same factor. For example, if X doubles, Y is halved. You can recognize it by checking if the product of the two variables remains constant (X × Y = k).

How do I solve inverse proportion problems step by step?

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Follow these steps: 1) Identify the inverse relationship, 2) Find the constant k using k = X₁ × Y₁, 3) Use the formula Y = k/X to find unknown values, 4) Verify your answer by checking that the product remains constant.

What's the difference between direct and inverse proportion?

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In direct proportion, both variables increase or decrease together (Y = kX). In inverse proportion, when one variable increases, the other decreases (Y = k/X). Direct proportion graphs as a straight line, while inverse proportion creates a hyperbola.

What are common real-world examples of inverse proportion?

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Common examples include: • Speed and travel time (faster speed = less time) • Number of workers and completion time • Brightness and distance from light source • Gas consumption and remaining fuel • Price per item and quantity bought with fixed budget

How do I check if a table shows inverse proportionality?

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Multiply each pair of X and Y values. If all products equal the same constant, it's inverse proportion. For example, if (5,20), (10,10), (20,5) gives products 100, 100, 100, then it shows inverse proportionality with k=100.

What does the graph of inverse proportion look like?

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The graph of Y = a/X is a hyperbola with two curved branches. It never touches the X or Y axes, approaches them asymptotically, and lies in the first and third quadrants when 'a' is positive.

How do I find the constant in inverse proportion problems?

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Use any complete pair of values from your data: k = X × Y. This constant remains the same for all pairs in an inverse relationship. Once you find k, you can use Y = k/X to solve for any missing values.

What are the most common mistakes in inverse proportion problems?

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Common mistakes include: confusing inverse with direct proportion, forgetting to multiply X and Y to find the constant, not checking that products are equal, and misreading whether one variable increases or decreases when solving word problems.

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