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Finding the Fourth Proportional to 660.69, 911.09 and 398.55

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Solution

The fourth proportional to 660.69, 911.09 and 398.55 is: 549.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.69 : 911.09 = 398.55 : x
  2. Step 2: Convert to fraction form
    660.69/911.09 = 398.55/x
  3. Step 3: Cross multiply
    660.69x = 911.09 × 398.55
  4. Step 4: Simplify right side
    660.69x = 363,112.93
  5. Step 5: Solve for x
    x = 363,112.93/660.69
  6. Step 6: Final answer
    x = 549.60

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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.