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Finding the Fourth Proportional to 429.40, 639.68 and 408.28

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Solution

The fourth proportional to 429.40, 639.68 and 408.28 is: 608.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.40 : 639.68 = 408.28 : x
  2. Step 2: Convert to fraction form
    429.40/639.68 = 408.28/x
  3. Step 3: Cross multiply
    429.40x = 639.68 × 408.28
  4. Step 4: Simplify right side
    429.40x = 261,168.55
  5. Step 5: Solve for x
    x = 261,168.55/429.40
  6. Step 6: Final answer
    x = 608.22

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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.