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Finding the Fourth Proportional to 667.95, 921.42 and 405.78

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Solution

The fourth proportional to 667.95, 921.42 and 405.78 is: 559.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.95 : 921.42 = 405.78 : x
  2. Step 2: Convert to fraction form
    667.95/921.42 = 405.78/x
  3. Step 3: Cross multiply
    667.95x = 921.42 × 405.78
  4. Step 4: Simplify right side
    667.95x = 373,893.81
  5. Step 5: Solve for x
    x = 373,893.81/667.95
  6. Step 6: Final answer
    x = 559.76

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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.