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Finding the Fourth Proportional to 208.41, 312.51 and 86.61

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Solution

The fourth proportional to 208.41, 312.51 and 86.61 is: 129.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.41 : 312.51 = 86.61 : x
  2. Step 2: Convert to fraction form
    208.41/312.51 = 86.61/x
  3. Step 3: Cross multiply
    208.41x = 312.51 × 86.61
  4. Step 4: Simplify right side
    208.41x = 27,066.49
  5. Step 5: Solve for x
    x = 27,066.49/208.41
  6. Step 6: Final answer
    x = 129.87

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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.