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Finding the Fourth Proportional to 640.20, 960.11 and 420.82

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Solution

The fourth proportional to 640.20, 960.11 and 420.82 is: 631.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.20 : 960.11 = 420.82 : x
  2. Step 2: Convert to fraction form
    640.20/960.11 = 420.82/x
  3. Step 3: Cross multiply
    640.20x = 960.11 × 420.82
  4. Step 4: Simplify right side
    640.20x = 404,030.56
  5. Step 5: Solve for x
    x = 404,030.56/640.20
  6. Step 6: Final answer
    x = 631.10

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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.