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Finding the Fourth Proportional to 143.72, 198.72 and 100.40

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Solution

The fourth proportional to 143.72, 198.72 and 100.40 is: 138.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.72 : 198.72 = 100.40 : x
  2. Step 2: Convert to fraction form
    143.72/198.72 = 100.40/x
  3. Step 3: Cross multiply
    143.72x = 198.72 × 100.40
  4. Step 4: Simplify right side
    143.72x = 19,951.49
  5. Step 5: Solve for x
    x = 19,951.49/143.72
  6. Step 6: Final answer
    x = 138.82

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.