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Finding the Fourth Proportional to 639.62, 959.77 and 420.24

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Solution

The fourth proportional to 639.62, 959.77 and 420.24 is: 630.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.62 : 959.77 = 420.24 : x
  2. Step 2: Convert to fraction form
    639.62/959.77 = 420.24/x
  3. Step 3: Cross multiply
    639.62x = 959.77 × 420.24
  4. Step 4: Simplify right side
    639.62x = 403,333.65
  5. Step 5: Solve for x
    x = 403,333.65/639.62
  6. Step 6: Final answer
    x = 630.58

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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.