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Finding the Fourth Proportional to 76.38, 105.86 and 61.98

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Solution

The fourth proportional to 76.38, 105.86 and 61.98 is: 85.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.38 : 105.86 = 61.98 : x
  2. Step 2: Convert to fraction form
    76.38/105.86 = 61.98/x
  3. Step 3: Cross multiply
    76.38x = 105.86 × 61.98
  4. Step 4: Simplify right side
    76.38x = 6,560.89
  5. Step 5: Solve for x
    x = 6,560.89/76.38
  6. Step 6: Final answer
    x = 85.90

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.