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Finding the Fourth Proportional to 143.37, 215.34 and 85.70

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Solution

The fourth proportional to 143.37, 215.34 and 85.70 is: 128.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.37 : 215.34 = 85.70 : x
  2. Step 2: Convert to fraction form
    143.37/215.34 = 85.70/x
  3. Step 3: Cross multiply
    143.37x = 215.34 × 85.70
  4. Step 4: Simplify right side
    143.37x = 18,454.64
  5. Step 5: Solve for x
    x = 18,454.64/143.37
  6. Step 6: Final answer
    x = 128.72

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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.