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Finding the Third Proportional to 121.50 and 139.13

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Solution

The third proportional to 121.50 and 139.13 is: 159.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.50 : 139.13 = 139.13 : x
  2. Step 2: Convert to fraction form
    121.50/139.13 = 139.13/x
  3. Step 3: Cross multiply
    121.50x = 139.13 × 139.13
  4. Step 4: Simplify right side
    121.50x = 19,355.77
  5. Step 5: Solve for x
    x = 19,355.77/121.50
  6. Step 6: Final answer
    x = 159.31

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Why These Related Problems?

These problems maintain the same ratio (1.15) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.