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Finding the Fourth Proportional to 90.49, 135.53 and 81.38

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Solution

The fourth proportional to 90.49, 135.53 and 81.38 is: 121.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.49 : 135.53 = 81.38 : x
  2. Step 2: Convert to fraction form
    90.49/135.53 = 81.38/x
  3. Step 3: Cross multiply
    90.49x = 135.53 × 81.38
  4. Step 4: Simplify right side
    90.49x = 11,029.43
  5. Step 5: Solve for x
    x = 11,029.43/90.49
  6. Step 6: Final answer
    x = 121.89

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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.