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Finding the Fourth Proportional to 215.72, 322.90 and 138.58

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Solution

The fourth proportional to 215.72, 322.90 and 138.58 is: 207.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.72 : 322.90 = 138.58 : x
  2. Step 2: Convert to fraction form
    215.72/322.90 = 138.58/x
  3. Step 3: Cross multiply
    215.72x = 322.90 × 138.58
  4. Step 4: Simplify right side
    215.72x = 44,747.48
  5. Step 5: Solve for x
    x = 44,747.48/215.72
  6. Step 6: Final answer
    x = 207.43

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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.