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Finding the Fourth Proportional to 775.31, 1,161.91 and 428.13

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Solution

The fourth proportional to 775.31, 1,161.91 and 428.13 is: 641.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    775.31 : 1,161.91 = 428.13 : x
  2. Step 2: Convert to fraction form
    775.31/1,161.91 = 428.13/x
  3. Step 3: Cross multiply
    775.31x = 1,161.91 × 428.13
  4. Step 4: Simplify right side
    775.31x = 497,442.72
  5. Step 5: Solve for x
    x = 497,442.72/775.31
  6. Step 6: Final answer
    x = 641.60

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.