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Finding the Fourth Proportional to 90.81, 135.81 and 86.63

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Solution

The fourth proportional to 90.81, 135.81 and 86.63 is: 129.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.81 : 135.81 = 86.63 : x
  2. Step 2: Convert to fraction form
    90.81/135.81 = 86.63/x
  3. Step 3: Cross multiply
    90.81x = 135.81 × 86.63
  4. Step 4: Simplify right side
    90.81x = 11,764.54
  5. Step 5: Solve for x
    x = 11,764.54/90.81
  6. Step 6: Final answer
    x = 129.55

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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.