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Finding the Fourth Proportional to 120.72, 180.90 and 55.71

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Solution

The fourth proportional to 120.72, 180.90 and 55.71 is: 83.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.72 : 180.90 = 55.71 : x
  2. Step 2: Convert to fraction form
    120.72/180.90 = 55.71/x
  3. Step 3: Cross multiply
    120.72x = 180.90 × 55.71
  4. Step 4: Simplify right side
    120.72x = 10,077.94
  5. Step 5: Solve for x
    x = 10,077.94/120.72
  6. Step 6: Final answer
    x = 83.48

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.