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Finding the Fourth Proportional to 208.07, 312.12 and 86.39

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Solution

The fourth proportional to 208.07, 312.12 and 86.39 is: 129.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.07 : 312.12 = 86.39 : x
  2. Step 2: Convert to fraction form
    208.07/312.12 = 86.39/x
  3. Step 3: Cross multiply
    208.07x = 312.12 × 86.39
  4. Step 4: Simplify right side
    208.07x = 26,964.05
  5. Step 5: Solve for x
    x = 26,964.05/208.07
  6. Step 6: Final answer
    x = 129.59

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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.