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Finding the Fourth Proportional to 81.90, 113 and 52.78

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Solution

The fourth proportional to 81.90, 113 and 52.78 is: 72.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.90 : 113 = 52.78 : x
  2. Step 2: Convert to fraction form
    81.90/113 = 52.78/x
  3. Step 3: Cross multiply
    81.90x = 113 × 52.78
  4. Step 4: Simplify right side
    81.90x = 5,964.14
  5. Step 5: Solve for x
    x = 5,964.14/81.90
  6. Step 6: Final answer
    x = 72.82

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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.