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Finding the Fourth Proportional to 639.08, 881.75 and 390.34

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Solution

The fourth proportional to 639.08, 881.75 and 390.34 is: 538.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.08 : 881.75 = 390.34 : x
  2. Step 2: Convert to fraction form
    639.08/881.75 = 390.34/x
  3. Step 3: Cross multiply
    639.08x = 881.75 × 390.34
  4. Step 4: Simplify right side
    639.08x = 344,182.30
  5. Step 5: Solve for x
    x = 344,182.30/639.08
  6. Step 6: Final answer
    x = 538.56

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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.