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Finding the Fourth Proportional to 137.81, 189.72 and 120.31

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Solution

The fourth proportional to 137.81, 189.72 and 120.31 is: 165.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.81 : 189.72 = 120.31 : x
  2. Step 2: Convert to fraction form
    137.81/189.72 = 120.31/x
  3. Step 3: Cross multiply
    137.81x = 189.72 × 120.31
  4. Step 4: Simplify right side
    137.81x = 22,824.74
  5. Step 5: Solve for x
    x = 22,824.74/137.81
  6. Step 6: Final answer
    x = 165.62

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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.