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Finding the Fourth Proportional to 90.76, 136.38 and 56.61

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Solution

The fourth proportional to 90.76, 136.38 and 56.61 is: 85.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.76 : 136.38 = 56.61 : x
  2. Step 2: Convert to fraction form
    90.76/136.38 = 56.61/x
  3. Step 3: Cross multiply
    90.76x = 136.38 × 56.61
  4. Step 4: Simplify right side
    90.76x = 7,720.47
  5. Step 5: Solve for x
    x = 7,720.47/90.76
  6. Step 6: Final answer
    x = 85.06

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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.