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Finding the Fourth Proportional to 660.78, 911.75 and 398.81

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Solution

The fourth proportional to 660.78, 911.75 and 398.81 is: 550.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.78 : 911.75 = 398.81 : x
  2. Step 2: Convert to fraction form
    660.78/911.75 = 398.81/x
  3. Step 3: Cross multiply
    660.78x = 911.75 × 398.81
  4. Step 4: Simplify right side
    660.78x = 363,613.02
  5. Step 5: Solve for x
    x = 363,613.02/660.78
  6. Step 6: Final answer
    x = 550.28

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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.