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Finding the Fourth Proportional to 81.02, 121.50 and 39.86

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Solution

The fourth proportional to 81.02, 121.50 and 39.86 is: 59.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.02 : 121.50 = 39.86 : x
  2. Step 2: Convert to fraction form
    81.02/121.50 = 39.86/x
  3. Step 3: Cross multiply
    81.02x = 121.50 × 39.86
  4. Step 4: Simplify right side
    81.02x = 4,842.99
  5. Step 5: Solve for x
    x = 4,842.99/81.02
  6. Step 6: Final answer
    x = 59.78

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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.