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Finding the Fourth Proportional to 769.56, 1,061.82 and 645.72

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Solution

The fourth proportional to 769.56, 1,061.82 and 645.72 is: 890.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.56 : 1,061.82 = 645.72 : x
  2. Step 2: Convert to fraction form
    769.56/1,061.82 = 645.72/x
  3. Step 3: Cross multiply
    769.56x = 1,061.82 × 645.72
  4. Step 4: Simplify right side
    769.56x = 685,638.41
  5. Step 5: Solve for x
    x = 685,638.41/769.56
  6. Step 6: Final answer
    x = 890.95

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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.