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Finding the Fourth Proportional to 89.85, 123.72 and 77.55

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Solution

The fourth proportional to 89.85, 123.72 and 77.55 is: 106.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.85 : 123.72 = 77.55 : x
  2. Step 2: Convert to fraction form
    89.85/123.72 = 77.55/x
  3. Step 3: Cross multiply
    89.85x = 123.72 × 77.55
  4. Step 4: Simplify right side
    89.85x = 9,594.49
  5. Step 5: Solve for x
    x = 9,594.49/89.85
  6. Step 6: Final answer
    x = 106.78

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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.