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Finding the Fourth Proportional to 385.05, 531.20 and 311.31

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Solution

The fourth proportional to 385.05, 531.20 and 311.31 is: 429.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    385.05 : 531.20 = 311.31 : x
  2. Step 2: Convert to fraction form
    385.05/531.20 = 311.31/x
  3. Step 3: Cross multiply
    385.05x = 531.20 × 311.31
  4. Step 4: Simplify right side
    385.05x = 165,366.32
  5. Step 5: Solve for x
    x = 165,366.32/385.05
  6. Step 6: Final answer
    x = 429.47

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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.