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Finding the Fourth Proportional to 90.20, 135.30 and 85

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Solution

The fourth proportional to 90.20, 135.30 and 85 is: 127.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.20 : 135.30 = 85 : x
  2. Step 2: Convert to fraction form
    90.20/135.30 = 85/x
  3. Step 3: Cross multiply
    90.20x = 135.30 × 85
  4. Step 4: Simplify right side
    90.20x = 11,500.50
  5. Step 5: Solve for x
    x = 11,500.50/90.20
  6. Step 6: Final answer
    x = 127.50

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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.