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Finding the Fourth Proportional to 90.71, 136.73 and 85.76

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Solution

The fourth proportional to 90.71, 136.73 and 85.76 is: 129.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.71 : 136.73 = 85.76 : x
  2. Step 2: Convert to fraction form
    90.71/136.73 = 85.76/x
  3. Step 3: Cross multiply
    90.71x = 136.73 × 85.76
  4. Step 4: Simplify right side
    90.71x = 11,725.96
  5. Step 5: Solve for x
    x = 11,725.96/90.71
  6. Step 6: Final answer
    x = 129.27

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.