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Finding the Fourth Proportional to 427.19, 640.72 and 138.56

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Solution

The fourth proportional to 427.19, 640.72 and 138.56 is: 207.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.19 : 640.72 = 138.56 : x
  2. Step 2: Convert to fraction form
    427.19/640.72 = 138.56/x
  3. Step 3: Cross multiply
    427.19x = 640.72 × 138.56
  4. Step 4: Simplify right side
    427.19x = 88,779.42
  5. Step 5: Solve for x
    x = 88,779.42/427.19
  6. Step 6: Final answer
    x = 207.82

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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.