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Finding the Fourth Proportional to 80.28, 121.17 and 78.42

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Solution

The fourth proportional to 80.28, 121.17 and 78.42 is: 118.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.28 : 121.17 = 78.42 : x
  2. Step 2: Convert to fraction form
    80.28/121.17 = 78.42/x
  3. Step 3: Cross multiply
    80.28x = 121.17 × 78.42
  4. Step 4: Simplify right side
    80.28x = 9,502.15
  5. Step 5: Solve for x
    x = 9,502.15/80.28
  6. Step 6: Final answer
    x = 118.36

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.