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Finding the Fourth Proportional to 655.78, 905.02 and 393.80

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Solution

The fourth proportional to 655.78, 905.02 and 393.80 is: 543.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    655.78 : 905.02 = 393.80 : x
  2. Step 2: Convert to fraction form
    655.78/905.02 = 393.80/x
  3. Step 3: Cross multiply
    655.78x = 905.02 × 393.80
  4. Step 4: Simplify right side
    655.78x = 356,396.88
  5. Step 5: Solve for x
    x = 356,396.88/655.78
  6. Step 6: Final answer
    x = 543.47

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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.