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Finding the Fourth Proportional to 143.78, 215.49 and 86

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Solution

The fourth proportional to 143.78, 215.49 and 86 is: 128.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.78 : 215.49 = 86 : x
  2. Step 2: Convert to fraction form
    143.78/215.49 = 86/x
  3. Step 3: Cross multiply
    143.78x = 215.49 × 86
  4. Step 4: Simplify right side
    143.78x = 18,532.14
  5. Step 5: Solve for x
    x = 18,532.14/143.78
  6. Step 6: Final answer
    x = 128.89

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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.