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Finding the Fourth Proportional to 660.40, 911.35 and 398.57

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Solution

The fourth proportional to 660.40, 911.35 and 398.57 is: 550.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.40 : 911.35 = 398.57 : x
  2. Step 2: Convert to fraction form
    660.40/911.35 = 398.57/x
  3. Step 3: Cross multiply
    660.40x = 911.35 × 398.57
  4. Step 4: Simplify right side
    660.40x = 363,232.71
  5. Step 5: Solve for x
    x = 363,232.71/660.40
  6. Step 6: Final answer
    x = 550.02

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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.