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Finding the Fourth Proportional to 660.80, 911.76 and 398.90

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Solution

The fourth proportional to 660.80, 911.76 and 398.90 is: 550.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.80 : 911.76 = 398.90 : x
  2. Step 2: Convert to fraction form
    660.80/911.76 = 398.90/x
  3. Step 3: Cross multiply
    660.80x = 911.76 × 398.90
  4. Step 4: Simplify right side
    660.80x = 363,701.06
  5. Step 5: Solve for x
    x = 363,701.06/660.80
  6. Step 6: Final answer
    x = 550.40

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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.