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Finding the Fourth Proportional to 89.78, 134.73 and 71.78

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Solution

The fourth proportional to 89.78, 134.73 and 71.78 is: 107.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.78 : 134.73 = 71.78 : x
  2. Step 2: Convert to fraction form
    89.78/134.73 = 71.78/x
  3. Step 3: Cross multiply
    89.78x = 134.73 × 71.78
  4. Step 4: Simplify right side
    89.78x = 9,670.25
  5. Step 5: Solve for x
    x = 9,670.25/89.78
  6. Step 6: Final answer
    x = 107.72

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.