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Finding the Fourth Proportional to 139.99, 193.18 and 81.78

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Solution

The fourth proportional to 139.99, 193.18 and 81.78 is: 112.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.99 : 193.18 = 81.78 : x
  2. Step 2: Convert to fraction form
    139.99/193.18 = 81.78/x
  3. Step 3: Cross multiply
    139.99x = 193.18 × 81.78
  4. Step 4: Simplify right side
    139.99x = 15,798.26
  5. Step 5: Solve for x
    x = 15,798.26/139.99
  6. Step 6: Final answer
    x = 112.85

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.