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Finding the Fourth Proportional to 80.72, 120.90 and 61.50

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Solution

The fourth proportional to 80.72, 120.90 and 61.50 is: 92.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.72 : 120.90 = 61.50 : x
  2. Step 2: Convert to fraction form
    80.72/120.90 = 61.50/x
  3. Step 3: Cross multiply
    80.72x = 120.90 × 61.50
  4. Step 4: Simplify right side
    80.72x = 7,435.35
  5. Step 5: Solve for x
    x = 7,435.35/80.72
  6. Step 6: Final answer
    x = 92.11

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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.