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Finding the Fourth Proportional to 80.64, 120.78 and 39.98

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Solution

The fourth proportional to 80.64, 120.78 and 39.98 is: 59.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.64 : 120.78 = 39.98 : x
  2. Step 2: Convert to fraction form
    80.64/120.78 = 39.98/x
  3. Step 3: Cross multiply
    80.64x = 120.78 × 39.98
  4. Step 4: Simplify right side
    80.64x = 4,828.78
  5. Step 5: Solve for x
    x = 4,828.78/80.64
  6. Step 6: Final answer
    x = 59.88

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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.