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Finding the Fourth Proportional to 208.42, 312.36 and 86.54

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Solution

The fourth proportional to 208.42, 312.36 and 86.54 is: 129.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.42 : 312.36 = 86.54 : x
  2. Step 2: Convert to fraction form
    208.42/312.36 = 86.54/x
  3. Step 3: Cross multiply
    208.42x = 312.36 × 86.54
  4. Step 4: Simplify right side
    208.42x = 27,031.63
  5. Step 5: Solve for x
    x = 27,031.63/208.42
  6. Step 6: Final answer
    x = 129.70

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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.