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Finding the Fourth Proportional to 663.78, 920.19 and 628.65

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Solution

The fourth proportional to 663.78, 920.19 and 628.65 is: 871.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    663.78 : 920.19 = 628.65 : x
  2. Step 2: Convert to fraction form
    663.78/920.19 = 628.65/x
  3. Step 3: Cross multiply
    663.78x = 920.19 × 628.65
  4. Step 4: Simplify right side
    663.78x = 578,477.44
  5. Step 5: Solve for x
    x = 578,477.44/663.78
  6. Step 6: Final answer
    x = 871.49

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.