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Finding the Fourth Proportional to 429.14, 643.79 and 140.78

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Solution

The fourth proportional to 429.14, 643.79 and 140.78 is: 211.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.14 : 643.79 = 140.78 : x
  2. Step 2: Convert to fraction form
    429.14/643.79 = 140.78/x
  3. Step 3: Cross multiply
    429.14x = 643.79 × 140.78
  4. Step 4: Simplify right side
    429.14x = 90,632.76
  5. Step 5: Solve for x
    x = 90,632.76/429.14
  6. Step 6: Final answer
    x = 211.20

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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.