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Finding the Fourth Proportional to 639.40, 881.46 and 429.20

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Solution

The fourth proportional to 639.40, 881.46 and 429.20 is: 591.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.40 : 881.46 = 429.20 : x
  2. Step 2: Convert to fraction form
    639.40/881.46 = 429.20/x
  3. Step 3: Cross multiply
    639.40x = 881.46 × 429.20
  4. Step 4: Simplify right side
    639.40x = 378,322.63
  5. Step 5: Solve for x
    x = 378,322.63/639.40
  6. Step 6: Final answer
    x = 591.68

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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.