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Finding the Fourth Proportional to 90.72, 136.08 and 54.60

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Solution

The fourth proportional to 90.72, 136.08 and 54.60 is: 81.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.72 : 136.08 = 54.60 : x
  2. Step 2: Convert to fraction form
    90.72/136.08 = 54.60/x
  3. Step 3: Cross multiply
    90.72x = 136.08 × 54.60
  4. Step 4: Simplify right side
    90.72x = 7,429.97
  5. Step 5: Solve for x
    x = 7,429.97/90.72
  6. Step 6: Final answer
    x = 81.90

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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.