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Finding the Fourth Proportional to 660.78, 911.94 and 398.79

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Solution

The fourth proportional to 660.78, 911.94 and 398.79 is: 550.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.78 : 911.94 = 398.79 : x
  2. Step 2: Convert to fraction form
    660.78/911.94 = 398.79/x
  3. Step 3: Cross multiply
    660.78x = 911.94 × 398.79
  4. Step 4: Simplify right side
    660.78x = 363,672.55
  5. Step 5: Solve for x
    x = 363,672.55/660.78
  6. Step 6: Final answer
    x = 550.37

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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.