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Finding the Fourth Proportional to 103.89, 155.90 and 86.07

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Solution

The fourth proportional to 103.89, 155.90 and 86.07 is: 129.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.89 : 155.90 = 86.07 : x
  2. Step 2: Convert to fraction form
    103.89/155.90 = 86.07/x
  3. Step 3: Cross multiply
    103.89x = 155.90 × 86.07
  4. Step 4: Simplify right side
    103.89x = 13,418.31
  5. Step 5: Solve for x
    x = 13,418.31/103.89
  6. Step 6: Final answer
    x = 129.16

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.