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Finding the Fourth Proportional to 420.39, 630.99 and 393.86

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Solution

The fourth proportional to 420.39, 630.99 and 393.86 is: 591.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.39 : 630.99 = 393.86 : x
  2. Step 2: Convert to fraction form
    420.39/630.99 = 393.86/x
  3. Step 3: Cross multiply
    420.39x = 630.99 × 393.86
  4. Step 4: Simplify right side
    420.39x = 248,523.30
  5. Step 5: Solve for x
    x = 248,523.30/420.39
  6. Step 6: Final answer
    x = 591.17

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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.