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Finding the Fourth Proportional to 661.10, 911.86 and 398.66

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Solution

The fourth proportional to 661.10, 911.86 and 398.66 is: 549.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.10 : 911.86 = 398.66 : x
  2. Step 2: Convert to fraction form
    661.10/911.86 = 398.66/x
  3. Step 3: Cross multiply
    661.10x = 911.86 × 398.66
  4. Step 4: Simplify right side
    661.10x = 363,516.55
  5. Step 5: Solve for x
    x = 363,516.55/661.10
  6. Step 6: Final answer
    x = 549.87

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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.