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Finding the Fourth Proportional to 81.17, 112.08 and 78.59

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Solution

The fourth proportional to 81.17, 112.08 and 78.59 is: 108.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.17 : 112.08 = 78.59 : x
  2. Step 2: Convert to fraction form
    81.17/112.08 = 78.59/x
  3. Step 3: Cross multiply
    81.17x = 112.08 × 78.59
  4. Step 4: Simplify right side
    81.17x = 8,808.37
  5. Step 5: Solve for x
    x = 8,808.37/81.17
  6. Step 6: Final answer
    x = 108.52

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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.