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Finding the Fourth Proportional to 211.91, 318.22 and 138.91

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Solution

The fourth proportional to 211.91, 318.22 and 138.91 is: 208.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.91 : 318.22 = 138.91 : x
  2. Step 2: Convert to fraction form
    211.91/318.22 = 138.91/x
  3. Step 3: Cross multiply
    211.91x = 318.22 × 138.91
  4. Step 4: Simplify right side
    211.91x = 44,203.94
  5. Step 5: Solve for x
    x = 44,203.94/211.91
  6. Step 6: Final answer
    x = 208.60

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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.