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Finding the Fourth Proportional to 839.48, 1,257.78 and 405.56

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Solution

The fourth proportional to 839.48, 1,257.78 and 405.56 is: 607.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.48 : 1,257.78 = 405.56 : x
  2. Step 2: Convert to fraction form
    839.48/1,257.78 = 405.56/x
  3. Step 3: Cross multiply
    839.48x = 1,257.78 × 405.56
  4. Step 4: Simplify right side
    839.48x = 510,105.26
  5. Step 5: Solve for x
    x = 510,105.26/839.48
  6. Step 6: Final answer
    x = 607.64

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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.