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Finding the Fourth Proportional to 679.60, 1,018.80 and 405.40

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Solution

The fourth proportional to 679.60, 1,018.80 and 405.40 is: 607.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.60 : 1,018.80 = 405.40 : x
  2. Step 2: Convert to fraction form
    679.60/1,018.80 = 405.40/x
  3. Step 3: Cross multiply
    679.60x = 1,018.80 × 405.40
  4. Step 4: Simplify right side
    679.60x = 413,021.52
  5. Step 5: Solve for x
    x = 413,021.52/679.60
  6. Step 6: Final answer
    x = 607.74

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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.