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Finding the Fourth Proportional to 639.90, 882.78 and 418.80

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Solution

The fourth proportional to 639.90, 882.78 and 418.80 is: 577.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.90 : 882.78 = 418.80 : x
  2. Step 2: Convert to fraction form
    639.90/882.78 = 418.80/x
  3. Step 3: Cross multiply
    639.90x = 882.78 × 418.80
  4. Step 4: Simplify right side
    639.90x = 369,708.26
  5. Step 5: Solve for x
    x = 369,708.26/639.90
  6. Step 6: Final answer
    x = 577.76

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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.