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Finding the Fourth Proportional to 639.97, 883.38 and 391.21

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Solution

The fourth proportional to 639.97, 883.38 and 391.21 is: 540.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.97 : 883.38 = 391.21 : x
  2. Step 2: Convert to fraction form
    639.97/883.38 = 391.21/x
  3. Step 3: Cross multiply
    639.97x = 883.38 × 391.21
  4. Step 4: Simplify right side
    639.97x = 345,587.09
  5. Step 5: Solve for x
    x = 345,587.09/639.97
  6. Step 6: Final answer
    x = 540.01

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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.