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Finding the Fourth Proportional to 143.63, 215.16 and 85.90

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Solution

The fourth proportional to 143.63, 215.16 and 85.90 is: 128.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.63 : 215.16 = 85.90 : x
  2. Step 2: Convert to fraction form
    143.63/215.16 = 85.90/x
  3. Step 3: Cross multiply
    143.63x = 215.16 × 85.90
  4. Step 4: Simplify right side
    143.63x = 18,481.91
  5. Step 5: Solve for x
    x = 18,481.91/143.63
  6. Step 6: Final answer
    x = 128.68

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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.