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Finding the Fourth Proportional to 769.72, 1,061.40 and 628.78

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Solution

The fourth proportional to 769.72, 1,061.40 and 628.78 is: 867.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.72 : 1,061.40 = 628.78 : x
  2. Step 2: Convert to fraction form
    769.72/1,061.40 = 628.78/x
  3. Step 3: Cross multiply
    769.72x = 1,061.40 × 628.78
  4. Step 4: Simplify right side
    769.72x = 667,387.09
  5. Step 5: Solve for x
    x = 667,387.09/769.72
  6. Step 6: Final answer
    x = 867.05

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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.