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Finding the Fourth Proportional to 90.31, 135.29 and 80.78

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Solution

The fourth proportional to 90.31, 135.29 and 80.78 is: 121.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.31 : 135.29 = 80.78 : x
  2. Step 2: Convert to fraction form
    90.31/135.29 = 80.78/x
  3. Step 3: Cross multiply
    90.31x = 135.29 × 80.78
  4. Step 4: Simplify right side
    90.31x = 10,928.73
  5. Step 5: Solve for x
    x = 10,928.73/90.31
  6. Step 6: Final answer
    x = 121.01

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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.