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Finding the Fourth Proportional to 345.40, 517.78 and 128.92

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Solution

The fourth proportional to 345.40, 517.78 and 128.92 is: 193.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    345.40 : 517.78 = 128.92 : x
  2. Step 2: Convert to fraction form
    345.40/517.78 = 128.92/x
  3. Step 3: Cross multiply
    345.40x = 517.78 × 128.92
  4. Step 4: Simplify right side
    345.40x = 66,752.20
  5. Step 5: Solve for x
    x = 66,752.20/345.40
  6. Step 6: Final answer
    x = 193.26

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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.