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Finding the Fourth Proportional to 128.90, 193.10 and 104.78

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Solution

The fourth proportional to 128.90, 193.10 and 104.78 is: 156.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.90 : 193.10 = 104.78 : x
  2. Step 2: Convert to fraction form
    128.90/193.10 = 104.78/x
  3. Step 3: Cross multiply
    128.90x = 193.10 × 104.78
  4. Step 4: Simplify right side
    128.90x = 20,233.02
  5. Step 5: Solve for x
    x = 20,233.02/128.90
  6. Step 6: Final answer
    x = 156.97

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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.