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Finding the Fourth Proportional to 643.20, 887.27 and 390.96

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Solution

The fourth proportional to 643.20, 887.27 and 390.96 is: 539.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.20 : 887.27 = 390.96 : x
  2. Step 2: Convert to fraction form
    643.20/887.27 = 390.96/x
  3. Step 3: Cross multiply
    643.20x = 887.27 × 390.96
  4. Step 4: Simplify right side
    643.20x = 346,885.12
  5. Step 5: Solve for x
    x = 346,885.12/643.20
  6. Step 6: Final answer
    x = 539.31

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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.