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Finding the Fourth Proportional to 668.42, 1,002.31 and 390.85

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Solution

The fourth proportional to 668.42, 1,002.31 and 390.85 is: 586.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    668.42 : 1,002.31 = 390.85 : x
  2. Step 2: Convert to fraction form
    668.42/1,002.31 = 390.85/x
  3. Step 3: Cross multiply
    668.42x = 1,002.31 × 390.85
  4. Step 4: Simplify right side
    668.42x = 391,756.35
  5. Step 5: Solve for x
    x = 391,756.35/668.42
  6. Step 6: Final answer
    x = 586.09

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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.