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Finding the Fourth Proportional to 89.85, 133.86 and 85.20

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Solution

The fourth proportional to 89.85, 133.86 and 85.20 is: 126.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.85 : 133.86 = 85.20 : x
  2. Step 2: Convert to fraction form
    89.85/133.86 = 85.20/x
  3. Step 3: Cross multiply
    89.85x = 133.86 × 85.20
  4. Step 4: Simplify right side
    89.85x = 11,404.87
  5. Step 5: Solve for x
    x = 11,404.87/89.85
  6. Step 6: Final answer
    x = 126.93

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.