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Finding the Fourth Proportional to 769.31, 1,061.66 and 420

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Solution

The fourth proportional to 769.31, 1,061.66 and 420 is: 579.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.31 : 1,061.66 = 420 : x
  2. Step 2: Convert to fraction form
    769.31/1,061.66 = 420/x
  3. Step 3: Cross multiply
    769.31x = 1,061.66 × 420
  4. Step 4: Simplify right side
    769.31x = 445,898.25
  5. Step 5: Solve for x
    x = 445,898.25/769.31
  6. Step 6: Final answer
    x = 579.61

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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.