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Finding the Fourth Proportional to 90.58, 135.72 and 81.49

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Solution

The fourth proportional to 90.58, 135.72 and 81.49 is: 122.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.58 : 135.72 = 81.49 : x
  2. Step 2: Convert to fraction form
    90.58/135.72 = 81.49/x
  3. Step 3: Cross multiply
    90.58x = 135.72 × 81.49
  4. Step 4: Simplify right side
    90.58x = 11,059.82
  5. Step 5: Solve for x
    x = 11,059.82/90.58
  6. Step 6: Final answer
    x = 122.10

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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.