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Finding the Fourth Proportional to 668.16, 921.76 and 392

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Solution

The fourth proportional to 668.16, 921.76 and 392 is: 540.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    668.16 : 921.76 = 392 : x
  2. Step 2: Convert to fraction form
    668.16/921.76 = 392/x
  3. Step 3: Cross multiply
    668.16x = 921.76 × 392
  4. Step 4: Simplify right side
    668.16x = 361,329.92
  5. Step 5: Solve for x
    x = 361,329.92/668.16
  6. Step 6: Final answer
    x = 540.78

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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.