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Finding the Fourth Proportional to 621.32, 857.20 and 388.40

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Solution

The fourth proportional to 621.32, 857.20 and 388.40 is: 535.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    621.32 : 857.20 = 388.40 : x
  2. Step 2: Convert to fraction form
    621.32/857.20 = 388.40/x
  3. Step 3: Cross multiply
    621.32x = 857.20 × 388.40
  4. Step 4: Simplify right side
    621.32x = 332,936.48
  5. Step 5: Solve for x
    x = 332,936.48/621.32
  6. Step 6: Final answer
    x = 535.85

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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.