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Finding the Fourth Proportional to 655.78, 905.10 and 393.88

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Solution

The fourth proportional to 655.78, 905.10 and 393.88 is: 543.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    655.78 : 905.10 = 393.88 : x
  2. Step 2: Convert to fraction form
    655.78/905.10 = 393.88/x
  3. Step 3: Cross multiply
    655.78x = 905.10 × 393.88
  4. Step 4: Simplify right side
    655.78x = 356,500.79
  5. Step 5: Solve for x
    x = 356,500.79/655.78
  6. Step 6: Final answer
    x = 543.63

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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.