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Finding the Fourth Proportional to 693.76, 1,039.36 and 405.76

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Solution

The fourth proportional to 693.76, 1,039.36 and 405.76 is: 607.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    693.76 : 1,039.36 = 405.76 : x
  2. Step 2: Convert to fraction form
    693.76/1,039.36 = 405.76/x
  3. Step 3: Cross multiply
    693.76x = 1,039.36 × 405.76
  4. Step 4: Simplify right side
    693.76x = 421,730.71
  5. Step 5: Solve for x
    x = 421,730.71/693.76
  6. Step 6: Final answer
    x = 607.89

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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.