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Finding the Fourth Proportional to 143.40, 215.15 and 128.09

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Solution

The fourth proportional to 143.40, 215.15 and 128.09 is: 192.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.40 : 215.15 = 128.09 : x
  2. Step 2: Convert to fraction form
    143.40/215.15 = 128.09/x
  3. Step 3: Cross multiply
    143.40x = 215.15 × 128.09
  4. Step 4: Simplify right side
    143.40x = 27,558.56
  5. Step 5: Solve for x
    x = 27,558.56/143.40
  6. Step 6: Final answer
    x = 192.18

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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.