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Finding the Fourth Proportional to 725.21, 1,000.78 and 393.64

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Solution

The fourth proportional to 725.21, 1,000.78 and 393.64 is: 543.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    725.21 : 1,000.78 = 393.64 : x
  2. Step 2: Convert to fraction form
    725.21/1,000.78 = 393.64/x
  3. Step 3: Cross multiply
    725.21x = 1,000.78 × 393.64
  4. Step 4: Simplify right side
    725.21x = 393,942.04
  5. Step 5: Solve for x
    x = 393,942.04/725.21
  6. Step 6: Final answer
    x = 543.21

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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.