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Finding the Fourth Proportional to 403.70, 557 and 390.56

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Solution

The fourth proportional to 403.70, 557 and 390.56 is: 538.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    403.70 : 557 = 390.56 : x
  2. Step 2: Convert to fraction form
    403.70/557 = 390.56/x
  3. Step 3: Cross multiply
    403.70x = 557 × 390.56
  4. Step 4: Simplify right side
    403.70x = 217,541.92
  5. Step 5: Solve for x
    x = 217,541.92/403.70
  6. Step 6: Final answer
    x = 538.87

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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.