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Finding the Fourth Proportional to 639.64, 882.78 and 406.72

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Solution

The fourth proportional to 639.64, 882.78 and 406.72 is: 561.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.64 : 882.78 = 406.72 : x
  2. Step 2: Convert to fraction form
    639.64/882.78 = 406.72/x
  3. Step 3: Cross multiply
    639.64x = 882.78 × 406.72
  4. Step 4: Simplify right side
    639.64x = 359,044.28
  5. Step 5: Solve for x
    x = 359,044.28/639.64
  6. Step 6: Final answer
    x = 561.32

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.