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Finding the Fourth Proportional to 89.73, 123.80 and 81

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Solution

The fourth proportional to 89.73, 123.80 and 81 is: 111.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.73 : 123.80 = 81 : x
  2. Step 2: Convert to fraction form
    89.73/123.80 = 81/x
  3. Step 3: Cross multiply
    89.73x = 123.80 × 81
  4. Step 4: Simplify right side
    89.73x = 10,027.40
  5. Step 5: Solve for x
    x = 10,027.40/89.73
  6. Step 6: Final answer
    x = 111.75

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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.