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Finding the Fourth Proportional to 639.76, 959.64 and 423.76

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Solution

The fourth proportional to 639.76, 959.64 and 423.76 is: 635.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.76 : 959.64 = 423.76 : x
  2. Step 2: Convert to fraction form
    639.76/959.64 = 423.76/x
  3. Step 3: Cross multiply
    639.76x = 959.64 × 423.76
  4. Step 4: Simplify right side
    639.76x = 406,657.05
  5. Step 5: Solve for x
    x = 406,657.05/639.76
  6. Step 6: Final answer
    x = 635.64

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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.