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Finding the Fourth Proportional to 661.05, 911.70 and 398.79

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Solution

The fourth proportional to 661.05, 911.70 and 398.79 is: 550.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.05 : 911.70 = 398.79 : x
  2. Step 2: Convert to fraction form
    661.05/911.70 = 398.79/x
  3. Step 3: Cross multiply
    661.05x = 911.70 × 398.79
  4. Step 4: Simplify right side
    661.05x = 363,576.84
  5. Step 5: Solve for x
    x = 363,576.84/661.05
  6. Step 6: Final answer
    x = 550.00

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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.