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Finding the Fourth Proportional to 660.35, 911.39 and 398.40

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Solution

The fourth proportional to 660.35, 911.39 and 398.40 is: 549.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.35 : 911.39 = 398.40 : x
  2. Step 2: Convert to fraction form
    660.35/911.39 = 398.40/x
  3. Step 3: Cross multiply
    660.35x = 911.39 × 398.40
  4. Step 4: Simplify right side
    660.35x = 363,095.78
  5. Step 5: Solve for x
    x = 363,095.78/660.35
  6. Step 6: Final answer
    x = 549.86

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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.