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Finding the Fourth Proportional to 639.78, 960.21 and 442.01

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Solution

The fourth proportional to 639.78, 960.21 and 442.01 is: 663.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.78 : 960.21 = 442.01 : x
  2. Step 2: Convert to fraction form
    639.78/960.21 = 442.01/x
  3. Step 3: Cross multiply
    639.78x = 960.21 × 442.01
  4. Step 4: Simplify right side
    639.78x = 424,417.62
  5. Step 5: Solve for x
    x = 424,417.62/639.78
  6. Step 6: Final answer
    x = 663.38

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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.