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Finding the Fourth Proportional to 211.92, 317.61 and 138.78

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Solution

The fourth proportional to 211.92, 317.61 and 138.78 is: 207.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.92 : 317.61 = 138.78 : x
  2. Step 2: Convert to fraction form
    211.92/317.61 = 138.78/x
  3. Step 3: Cross multiply
    211.92x = 317.61 × 138.78
  4. Step 4: Simplify right side
    211.92x = 44,077.92
  5. Step 5: Solve for x
    x = 44,077.92/211.92
  6. Step 6: Final answer
    x = 207.99

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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.