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Finding the Fourth Proportional to 208.31, 312.50 and 86.51

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Solution

The fourth proportional to 208.31, 312.50 and 86.51 is: 129.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.31 : 312.50 = 86.51 : x
  2. Step 2: Convert to fraction form
    208.31/312.50 = 86.51/x
  3. Step 3: Cross multiply
    208.31x = 312.50 × 86.51
  4. Step 4: Simplify right side
    208.31x = 27,034.38
  5. Step 5: Solve for x
    x = 27,034.38/208.31
  6. Step 6: Final answer
    x = 129.78

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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.