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Finding the Fourth Proportional to 720.11, 993.78 and 405.38

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Solution

The fourth proportional to 720.11, 993.78 and 405.38 is: 559.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.11 : 993.78 = 405.38 : x
  2. Step 2: Convert to fraction form
    720.11/993.78 = 405.38/x
  3. Step 3: Cross multiply
    720.11x = 993.78 × 405.38
  4. Step 4: Simplify right side
    720.11x = 402,853.57
  5. Step 5: Solve for x
    x = 402,853.57/720.11
  6. Step 6: Final answer
    x = 559.44

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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.