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Finding the Fourth Proportional to 639.74, 958.80 and 408.55

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Solution

The fourth proportional to 639.74, 958.80 and 408.55 is: 612.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.74 : 958.80 = 408.55 : x
  2. Step 2: Convert to fraction form
    639.74/958.80 = 408.55/x
  3. Step 3: Cross multiply
    639.74x = 958.80 × 408.55
  4. Step 4: Simplify right side
    639.74x = 391,717.74
  5. Step 5: Solve for x
    x = 391,717.74/639.74
  6. Step 6: Final answer
    x = 612.31

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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.