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Finding the Fourth Proportional to 667.89, 921.78 and 405.90

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Solution

The fourth proportional to 667.89, 921.78 and 405.90 is: 560.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.89 : 921.78 = 405.90 : x
  2. Step 2: Convert to fraction form
    667.89/921.78 = 405.90/x
  3. Step 3: Cross multiply
    667.89x = 921.78 × 405.90
  4. Step 4: Simplify right side
    667.89x = 374,150.50
  5. Step 5: Solve for x
    x = 374,150.50/667.89
  6. Step 6: Final answer
    x = 560.20

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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.