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Finding the Fourth Proportional to 393.78, 543.09 and 355.38

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Solution

The fourth proportional to 393.78, 543.09 and 355.38 is: 490.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.78 : 543.09 = 355.38 : x
  2. Step 2: Convert to fraction form
    393.78/543.09 = 355.38/x
  3. Step 3: Cross multiply
    393.78x = 543.09 × 355.38
  4. Step 4: Simplify right side
    393.78x = 193,003.32
  5. Step 5: Solve for x
    x = 193,003.32/393.78
  6. Step 6: Final answer
    x = 490.13

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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.