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Finding the Fourth Proportional to 667.69, 921.39 and 387.91

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Solution

The fourth proportional to 667.69, 921.39 and 387.91 is: 535.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.69 : 921.39 = 387.91 : x
  2. Step 2: Convert to fraction form
    667.69/921.39 = 387.91/x
  3. Step 3: Cross multiply
    667.69x = 921.39 × 387.91
  4. Step 4: Simplify right side
    667.69x = 357,414.09
  5. Step 5: Solve for x
    x = 357,414.09/667.69
  6. Step 6: Final answer
    x = 535.30

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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.