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Finding the Fourth Proportional to 667.44, 921.21 and 387.72

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Solution

The fourth proportional to 667.44, 921.21 and 387.72 is: 535.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.44 : 921.21 = 387.72 : x
  2. Step 2: Convert to fraction form
    667.44/921.21 = 387.72/x
  3. Step 3: Cross multiply
    667.44x = 921.21 × 387.72
  4. Step 4: Simplify right side
    667.44x = 357,171.54
  5. Step 5: Solve for x
    x = 357,171.54/667.44
  6. Step 6: Final answer
    x = 535.14

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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.