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Finding the Fourth Proportional to 420.38, 630.66 and 390.38

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Solution

The fourth proportional to 420.38, 630.66 and 390.38 is: 585.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.38 : 630.66 = 390.38 : x
  2. Step 2: Convert to fraction form
    420.38/630.66 = 390.38/x
  3. Step 3: Cross multiply
    420.38x = 630.66 × 390.38
  4. Step 4: Simplify right side
    420.38x = 246,197.05
  5. Step 5: Solve for x
    x = 246,197.05/420.38
  6. Step 6: Final answer
    x = 585.65

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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.