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Finding the Fourth Proportional to 90.30, 123.78 and 89.09

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Solution

The fourth proportional to 90.30, 123.78 and 89.09 is: 122.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.30 : 123.78 = 89.09 : x
  2. Step 2: Convert to fraction form
    90.30/123.78 = 89.09/x
  3. Step 3: Cross multiply
    90.30x = 123.78 × 89.09
  4. Step 4: Simplify right side
    90.30x = 11,027.56
  5. Step 5: Solve for x
    x = 11,027.56/90.30
  6. Step 6: Final answer
    x = 122.12

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.