Home / 309-400

Finding the Third Proportional to 309 and 400

Calculator

Solution

The third proportional to 309 and 400 is: 517.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    309 : 400 = 400 : x
  2. Step 2: Convert to fraction form
    309/400 = 400/x
  3. Step 3: Cross multiply
    309x = 400 × 400
  4. Step 4: Simplify right side
    309x = 160,000
  5. Step 5: Solve for x
    x = 160,000/309
  6. Step 6: Final answer
    x = 517.80

Related Problems

Find third proportional to 154.50 and 200
Half scale
Find third proportional to 618 and 800
Double scale
Find third proportional to 311 and 403
Similar ratio
Find third proportional to 463.50 and 600
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.29) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.