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Finding the Fourth Proportional to 345.78, 518.35 and 129.21

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Solution

The fourth proportional to 345.78, 518.35 and 129.21 is: 193.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    345.78 : 518.35 = 129.21 : x
  2. Step 2: Convert to fraction form
    345.78/518.35 = 129.21/x
  3. Step 3: Cross multiply
    345.78x = 518.35 × 129.21
  4. Step 4: Simplify right side
    345.78x = 66,976.00
  5. Step 5: Solve for x
    x = 66,976.00/345.78
  6. Step 6: Final answer
    x = 193.70

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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.