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Finding the Fourth Proportional to 667.45, 921.07 and 387.75

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Solution

The fourth proportional to 667.45, 921.07 and 387.75 is: 535.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.45 : 921.07 = 387.75 : x
  2. Step 2: Convert to fraction form
    667.45/921.07 = 387.75/x
  3. Step 3: Cross multiply
    667.45x = 921.07 × 387.75
  4. Step 4: Simplify right side
    667.45x = 357,144.89
  5. Step 5: Solve for x
    x = 357,144.89/667.45
  6. Step 6: Final answer
    x = 535.09

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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.