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Finding the Fourth Proportional to 61.69, 85.10 and 39.86

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Solution

The fourth proportional to 61.69, 85.10 and 39.86 is: 54.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.69 : 85.10 = 39.86 : x
  2. Step 2: Convert to fraction form
    61.69/85.10 = 39.86/x
  3. Step 3: Cross multiply
    61.69x = 85.10 × 39.86
  4. Step 4: Simplify right side
    61.69x = 3,391.66
  5. Step 5: Solve for x
    x = 3,391.66/61.69
  6. Step 6: Final answer
    x = 54.98

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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.