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Finding the Fourth Proportional to 667.80, 921.56 and 405.64

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Solution

The fourth proportional to 667.80, 921.56 and 405.64 is: 559.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.80 : 921.56 = 405.64 : x
  2. Step 2: Convert to fraction form
    667.80/921.56 = 405.64/x
  3. Step 3: Cross multiply
    667.80x = 921.56 × 405.64
  4. Step 4: Simplify right side
    667.80x = 373,821.60
  5. Step 5: Solve for x
    x = 373,821.60/667.80
  6. Step 6: Final answer
    x = 559.78

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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.