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Finding the Fourth Proportional to 420.66, 580.86 and 311.31

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Solution

The fourth proportional to 420.66, 580.86 and 311.31 is: 429.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.66 : 580.86 = 311.31 : x
  2. Step 2: Convert to fraction form
    420.66/580.86 = 311.31/x
  3. Step 3: Cross multiply
    420.66x = 580.86 × 311.31
  4. Step 4: Simplify right side
    420.66x = 180,827.53
  5. Step 5: Solve for x
    x = 180,827.53/420.66
  6. Step 6: Final answer
    x = 429.87

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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.