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Finding the Fourth Proportional to 142.39, 213.72 and 91.09

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Solution

The fourth proportional to 142.39, 213.72 and 91.09 is: 136.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.39 : 213.72 = 91.09 : x
  2. Step 2: Convert to fraction form
    142.39/213.72 = 91.09/x
  3. Step 3: Cross multiply
    142.39x = 213.72 × 91.09
  4. Step 4: Simplify right side
    142.39x = 19,467.75
  5. Step 5: Solve for x
    x = 19,467.75/142.39
  6. Step 6: Final answer
    x = 136.72

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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.