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Finding the Fourth Proportional to 839, 1,257.60 and 405.20

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Solution

The fourth proportional to 839, 1,257.60 and 405.20 is: 607.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    839 : 1,257.60 = 405.20 : x
  2. Step 2: Convert to fraction form
    839/1,257.60 = 405.20/x
  3. Step 3: Cross multiply
    839x = 1,257.60 × 405.20
  4. Step 4: Simplify right side
    839x = 509,579.52
  5. Step 5: Solve for x
    x = 509,579.52/839
  6. Step 6: Final answer
    x = 607.37

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.