Home / 69-109

Finding the Third Proportional to 69 and 109

Calculator

Solution

The third proportional to 69 and 109 is: 172.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    69 : 109 = 109 : x
  2. Step 2: Convert to fraction form
    69/109 = 109/x
  3. Step 3: Cross multiply
    69x = 109 × 109
  4. Step 4: Simplify right side
    69x = 11,881
  5. Step 5: Solve for x
    x = 11,881/69
  6. Step 6: Final answer
    x = 172.19

Related Problems

Find third proportional to 34.50 and 54.50
Half scale
Find third proportional to 138 and 218
Double scale
Find third proportional to 71 and 112
Similar ratio
Find third proportional to 103.50 and 163.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.58) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.