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Finding the Fourth Proportional to 80.38, 120.71 and 78.90

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Solution

The fourth proportional to 80.38, 120.71 and 78.90 is: 118.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.38 : 120.71 = 78.90 : x
  2. Step 2: Convert to fraction form
    80.38/120.71 = 78.90/x
  3. Step 3: Cross multiply
    80.38x = 120.71 × 78.90
  4. Step 4: Simplify right side
    80.38x = 9,524.02
  5. Step 5: Solve for x
    x = 9,524.02/80.38
  6. Step 6: Final answer
    x = 118.49

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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.