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Finding the Fourth Proportional to 90.98, 136.50 and 86.38

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Solution

The fourth proportional to 90.98, 136.50 and 86.38 is: 129.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.98 : 136.50 = 86.38 : x
  2. Step 2: Convert to fraction form
    90.98/136.50 = 86.38/x
  3. Step 3: Cross multiply
    90.98x = 136.50 × 86.38
  4. Step 4: Simplify right side
    90.98x = 11,790.87
  5. Step 5: Solve for x
    x = 11,790.87/90.98
  6. Step 6: Final answer
    x = 129.60

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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.