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Finding the Fourth Proportional to 1,286.60, 1,930.20 and 420.92

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Solution

The fourth proportional to 1,286.60, 1,930.20 and 420.92 is: 631.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.60 : 1,930.20 = 420.92 : x
  2. Step 2: Convert to fraction form
    1,286.60/1,930.20 = 420.92/x
  3. Step 3: Cross multiply
    1,286.60x = 1,930.20 × 420.92
  4. Step 4: Simplify right side
    1,286.60x = 812,459.78
  5. Step 5: Solve for x
    x = 812,459.78/1,286.60
  6. Step 6: Final answer
    x = 631.48

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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.