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Finding the Fourth Proportional to 90.75, 136 and 81.55

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Solution

The fourth proportional to 90.75, 136 and 81.55 is: 122.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.75 : 136 = 81.55 : x
  2. Step 2: Convert to fraction form
    90.75/136 = 81.55/x
  3. Step 3: Cross multiply
    90.75x = 136 × 81.55
  4. Step 4: Simplify right side
    90.75x = 11,090.80
  5. Step 5: Solve for x
    x = 11,090.80/90.75
  6. Step 6: Final answer
    x = 122.21

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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.