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Finding the Fourth Proportional to 858.40, 1,286.96 and 425.86

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Solution

The fourth proportional to 858.40, 1,286.96 and 425.86 is: 638.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.40 : 1,286.96 = 425.86 : x
  2. Step 2: Convert to fraction form
    858.40/1,286.96 = 425.86/x
  3. Step 3: Cross multiply
    858.40x = 1,286.96 × 425.86
  4. Step 4: Simplify right side
    858.40x = 548,059.44
  5. Step 5: Solve for x
    x = 548,059.44/858.40
  6. Step 6: Final answer
    x = 638.47

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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.