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Finding the Fourth Proportional to 103.78, 155.43 and 86.35

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Solution

The fourth proportional to 103.78, 155.43 and 86.35 is: 129.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.78 : 155.43 = 86.35 : x
  2. Step 2: Convert to fraction form
    103.78/155.43 = 86.35/x
  3. Step 3: Cross multiply
    103.78x = 155.43 × 86.35
  4. Step 4: Simplify right side
    103.78x = 13,421.38
  5. Step 5: Solve for x
    x = 13,421.38/103.78
  6. Step 6: Final answer
    x = 129.33

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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.