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Finding the Fourth Proportional to 667.99, 921.64 and 388.21

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Solution

The fourth proportional to 667.99, 921.64 and 388.21 is: 535.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.99 : 921.64 = 388.21 : x
  2. Step 2: Convert to fraction form
    667.99/921.64 = 388.21/x
  3. Step 3: Cross multiply
    667.99x = 921.64 × 388.21
  4. Step 4: Simplify right side
    667.99x = 357,789.86
  5. Step 5: Solve for x
    x = 357,789.86/667.99
  6. Step 6: Final answer
    x = 535.62

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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.