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Finding the Fourth Proportional to 345.30, 517.78 and 128.72

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Solution

The fourth proportional to 345.30, 517.78 and 128.72 is: 193.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    345.30 : 517.78 = 128.72 : x
  2. Step 2: Convert to fraction form
    345.30/517.78 = 128.72/x
  3. Step 3: Cross multiply
    345.30x = 517.78 × 128.72
  4. Step 4: Simplify right side
    345.30x = 66,648.64
  5. Step 5: Solve for x
    x = 66,648.64/345.30
  6. Step 6: Final answer
    x = 193.02

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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.