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Finding the Fourth Proportional to 90.39, 135.45 and 76.89

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Solution

The fourth proportional to 90.39, 135.45 and 76.89 is: 115.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.39 : 135.45 = 76.89 : x
  2. Step 2: Convert to fraction form
    90.39/135.45 = 76.89/x
  3. Step 3: Cross multiply
    90.39x = 135.45 × 76.89
  4. Step 4: Simplify right side
    90.39x = 10,414.75
  5. Step 5: Solve for x
    x = 10,414.75/90.39
  6. Step 6: Final answer
    x = 115.22

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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.