Home / 4-20

Finding the Third Proportional to 4 and 20

Calculator

Solution

The third proportional to 4 and 20 is: 100

Step by Step Solution

  1. Step 1: Write the proportion equation
    4 : 20 = 20 : x
  2. Step 2: Convert to fraction form
    4/20 = 20/x
  3. Step 3: Cross multiply
    4x = 20 × 20
  4. Step 4: Simplify right side
    4x = 400
  5. Step 5: Solve for x
    x = 400/4
  6. Step 6: Final answer
    x = 100

Related Problems

Find third proportional to 2 and 10
Half scale
Find third proportional to 8 and 40
Double scale
Find third proportional to 6 and 30
Similar ratio
Find third proportional to 6 and 30
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (5) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.