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Finding the Fourth Proportional to 137.18, 189.28 and 81.91

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Solution

The fourth proportional to 137.18, 189.28 and 81.91 is: 113.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.18 : 189.28 = 81.91 : x
  2. Step 2: Convert to fraction form
    137.18/189.28 = 81.91/x
  3. Step 3: Cross multiply
    137.18x = 189.28 × 81.91
  4. Step 4: Simplify right side
    137.18x = 15,502.98
  5. Step 5: Solve for x
    x = 15,502.98/137.18
  6. Step 6: Final answer
    x = 113.02

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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.