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Finding the Fourth Proportional to 90.81, 136.25 and 71.61

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Solution

The fourth proportional to 90.81, 136.25 and 71.61 is: 107.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.81 : 136.25 = 71.61 : x
  2. Step 2: Convert to fraction form
    90.81/136.25 = 71.61/x
  3. Step 3: Cross multiply
    90.81x = 136.25 × 71.61
  4. Step 4: Simplify right side
    90.81x = 9,756.50
  5. Step 5: Solve for x
    x = 9,756.50/90.81
  6. Step 6: Final answer
    x = 107.44

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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.