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Finding the Fourth Proportional to 420.70, 580.39 and 287.71

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Solution

The fourth proportional to 420.70, 580.39 and 287.71 is: 396.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.70 : 580.39 = 287.71 : x
  2. Step 2: Convert to fraction form
    420.70/580.39 = 287.71/x
  3. Step 3: Cross multiply
    420.70x = 580.39 × 287.71
  4. Step 4: Simplify right side
    420.70x = 166,984.01
  5. Step 5: Solve for x
    x = 166,984.01/420.70
  6. Step 6: Final answer
    x = 396.92

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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.