Home / 209-309

Finding the Third Proportional to 209 and 309

Calculator

Solution

The third proportional to 209 and 309 is: 456.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    209 : 309 = 309 : x
  2. Step 2: Convert to fraction form
    209/309 = 309/x
  3. Step 3: Cross multiply
    209x = 309 × 309
  4. Step 4: Simplify right side
    209x = 95,481
  5. Step 5: Solve for x
    x = 95,481/209
  6. Step 6: Final answer
    x = 456.85

Related Problems

Find third proportional to 104.50 and 154.50
Half scale
Find third proportional to 418 and 618
Double scale
Find third proportional to 211 and 312
Similar ratio
Find third proportional to 313.50 and 463.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.48) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.