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Finding the Fourth Proportional to 143.28, 215.28 and 128.88

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Solution

The fourth proportional to 143.28, 215.28 and 128.88 is: 193.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.28 : 215.28 = 128.88 : x
  2. Step 2: Convert to fraction form
    143.28/215.28 = 128.88/x
  3. Step 3: Cross multiply
    143.28x = 215.28 × 128.88
  4. Step 4: Simplify right side
    143.28x = 27,745.29
  5. Step 5: Solve for x
    x = 27,745.29/143.28
  6. Step 6: Final answer
    x = 193.64

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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.