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Finding the Fourth Proportional to 138.98, 191.70 and 115.78

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Solution

The fourth proportional to 138.98, 191.70 and 115.78 is: 159.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.98 : 191.70 = 115.78 : x
  2. Step 2: Convert to fraction form
    138.98/191.70 = 115.78/x
  3. Step 3: Cross multiply
    138.98x = 191.70 × 115.78
  4. Step 4: Simplify right side
    138.98x = 22,195.03
  5. Step 5: Solve for x
    x = 22,195.03/138.98
  6. Step 6: Final answer
    x = 159.70

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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.