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Finding the Fourth Proportional to 143.46, 215.59 and 85.69

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Solution

The fourth proportional to 143.46, 215.59 and 85.69 is: 128.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.46 : 215.59 = 85.69 : x
  2. Step 2: Convert to fraction form
    143.46/215.59 = 85.69/x
  3. Step 3: Cross multiply
    143.46x = 215.59 × 85.69
  4. Step 4: Simplify right side
    143.46x = 18,473.91
  5. Step 5: Solve for x
    x = 18,473.91/143.46
  6. Step 6: Final answer
    x = 128.77

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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.