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Finding the Fourth Proportional to 126.80, 189.76 and 86.12

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Solution

The fourth proportional to 126.80, 189.76 and 86.12 is: 128.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.80 : 189.76 = 86.12 : x
  2. Step 2: Convert to fraction form
    126.80/189.76 = 86.12/x
  3. Step 3: Cross multiply
    126.80x = 189.76 × 86.12
  4. Step 4: Simplify right side
    126.80x = 16,342.13
  5. Step 5: Solve for x
    x = 16,342.13/126.80
  6. Step 6: Final answer
    x = 128.88

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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.