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Finding the Fourth Proportional to 643.32, 887.60 and 391.36

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Solution

The fourth proportional to 643.32, 887.60 and 391.36 is: 539.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.32 : 887.60 = 391.36 : x
  2. Step 2: Convert to fraction form
    643.32/887.60 = 391.36/x
  3. Step 3: Cross multiply
    643.32x = 887.60 × 391.36
  4. Step 4: Simplify right side
    643.32x = 347,371.14
  5. Step 5: Solve for x
    x = 347,371.14/643.32
  6. Step 6: Final answer
    x = 539.97

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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.