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Finding the Fourth Proportional to 667.78, 921.54 and 405.74

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Solution

The fourth proportional to 667.78, 921.54 and 405.74 is: 559.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.78 : 921.54 = 405.74 : x
  2. Step 2: Convert to fraction form
    667.78/921.54 = 405.74/x
  3. Step 3: Cross multiply
    667.78x = 921.54 × 405.74
  4. Step 4: Simplify right side
    667.78x = 373,905.64
  5. Step 5: Solve for x
    x = 373,905.64/667.78
  6. Step 6: Final answer
    x = 559.92

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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.