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Finding the Fourth Proportional to 208.19, 312.05 and 86.30

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Solution

The fourth proportional to 208.19, 312.05 and 86.30 is: 129.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.19 : 312.05 = 86.30 : x
  2. Step 2: Convert to fraction form
    208.19/312.05 = 86.30/x
  3. Step 3: Cross multiply
    208.19x = 312.05 × 86.30
  4. Step 4: Simplify right side
    208.19x = 26,927.92
  5. Step 5: Solve for x
    x = 26,927.92/208.19
  6. Step 6: Final answer
    x = 129.35

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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.