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Finding the Fourth Proportional to 208.71, 312.96 and 76.88

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Solution

The fourth proportional to 208.71, 312.96 and 76.88 is: 115.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.71 : 312.96 = 76.88 : x
  2. Step 2: Convert to fraction form
    208.71/312.96 = 76.88/x
  3. Step 3: Cross multiply
    208.71x = 312.96 × 76.88
  4. Step 4: Simplify right side
    208.71x = 24,061.44
  5. Step 5: Solve for x
    x = 24,061.44/208.71
  6. Step 6: Final answer
    x = 115.29

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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.