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Finding the Fourth Proportional to 80.78, 121.17 and 40.20

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Solution

The fourth proportional to 80.78, 121.17 and 40.20 is: 60.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.78 : 121.17 = 40.20 : x
  2. Step 2: Convert to fraction form
    80.78/121.17 = 40.20/x
  3. Step 3: Cross multiply
    80.78x = 121.17 × 40.20
  4. Step 4: Simplify right side
    80.78x = 4,870.93
  5. Step 5: Solve for x
    x = 4,870.93/80.78
  6. Step 6: Final answer
    x = 60.30

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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.