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Finding the Fourth Proportional to 90.79, 135.36 and 81.94

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Solution

The fourth proportional to 90.79, 135.36 and 81.94 is: 122.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.79 : 135.36 = 81.94 : x
  2. Step 2: Convert to fraction form
    90.79/135.36 = 81.94/x
  3. Step 3: Cross multiply
    90.79x = 135.36 × 81.94
  4. Step 4: Simplify right side
    90.79x = 11,091.40
  5. Step 5: Solve for x
    x = 11,091.40/90.79
  6. Step 6: Final answer
    x = 122.17

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.