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Finding the Fourth Proportional to 90.78, 125.13 and 71.09

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Solution

The fourth proportional to 90.78, 125.13 and 71.09 is: 97.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.78 : 125.13 = 71.09 : x
  2. Step 2: Convert to fraction form
    90.78/125.13 = 71.09/x
  3. Step 3: Cross multiply
    90.78x = 125.13 × 71.09
  4. Step 4: Simplify right side
    90.78x = 8,895.49
  5. Step 5: Solve for x
    x = 8,895.49/90.78
  6. Step 6: Final answer
    x = 97.99

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.