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Finding the Fourth Proportional to 138.72, 191.28 and 89.58

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Solution

The fourth proportional to 138.72, 191.28 and 89.58 is: 123.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.72 : 191.28 = 89.58 : x
  2. Step 2: Convert to fraction form
    138.72/191.28 = 89.58/x
  3. Step 3: Cross multiply
    138.72x = 191.28 × 89.58
  4. Step 4: Simplify right side
    138.72x = 17,134.86
  5. Step 5: Solve for x
    x = 17,134.86/138.72
  6. Step 6: Final answer
    x = 123.52

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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.