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Finding the Fourth Proportional to 80.96, 120.81 and 78.90

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Solution

The fourth proportional to 80.96, 120.81 and 78.90 is: 117.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.96 : 120.81 = 78.90 : x
  2. Step 2: Convert to fraction form
    80.96/120.81 = 78.90/x
  3. Step 3: Cross multiply
    80.96x = 120.81 × 78.90
  4. Step 4: Simplify right side
    80.96x = 9,531.91
  5. Step 5: Solve for x
    x = 9,531.91/80.96
  6. Step 6: Final answer
    x = 117.74

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.