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Finding the Fourth Proportional to 90.81, 135.69 and 87.57

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Solution

The fourth proportional to 90.81, 135.69 and 87.57 is: 130.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.81 : 135.69 = 87.57 : x
  2. Step 2: Convert to fraction form
    90.81/135.69 = 87.57/x
  3. Step 3: Cross multiply
    90.81x = 135.69 × 87.57
  4. Step 4: Simplify right side
    90.81x = 11,882.37
  5. Step 5: Solve for x
    x = 11,882.37/90.81
  6. Step 6: Final answer
    x = 130.85

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.