Home / 129-139

Finding the Third Proportional to 129 and 139

Calculator

Solution

The third proportional to 129 and 139 is: 149.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    129 : 139 = 139 : x
  2. Step 2: Convert to fraction form
    129/139 = 139/x
  3. Step 3: Cross multiply
    129x = 139 × 139
  4. Step 4: Simplify right side
    129x = 19,321
  5. Step 5: Solve for x
    x = 19,321/129
  6. Step 6: Final answer
    x = 149.78

Related Problems

Find third proportional to 64.50 and 69.50
Half scale
Find third proportional to 258 and 278
Double scale
Find third proportional to 131 and 141
Similar ratio
Find third proportional to 193.50 and 208.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.08) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.