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Finding the Fourth Proportional to 143.68, 213.76 and 138.40

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Solution

The fourth proportional to 143.68, 213.76 and 138.40 is: 205.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.68 : 213.76 = 138.40 : x
  2. Step 2: Convert to fraction form
    143.68/213.76 = 138.40/x
  3. Step 3: Cross multiply
    143.68x = 213.76 × 138.40
  4. Step 4: Simplify right side
    143.68x = 29,584.38
  5. Step 5: Solve for x
    x = 29,584.38/143.68
  6. Step 6: Final answer
    x = 205.90

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.