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Finding the Fourth Proportional to 420.21, 580.47 and 399.70

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Solution

The fourth proportional to 420.21, 580.47 and 399.70 is: 552.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.21 : 580.47 = 399.70 : x
  2. Step 2: Convert to fraction form
    420.21/580.47 = 399.70/x
  3. Step 3: Cross multiply
    420.21x = 580.47 × 399.70
  4. Step 4: Simplify right side
    420.21x = 232,011.86
  5. Step 5: Solve for x
    x = 232,011.86/420.21
  6. Step 6: Final answer
    x = 552.14

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.