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Finding the Fourth Proportional to 858.60, 1,287.90 and 425.79

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Solution

The fourth proportional to 858.60, 1,287.90 and 425.79 is: 638.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.60 : 1,287.90 = 425.79 : x
  2. Step 2: Convert to fraction form
    858.60/1,287.90 = 425.79/x
  3. Step 3: Cross multiply
    858.60x = 1,287.90 × 425.79
  4. Step 4: Simplify right side
    858.60x = 548,374.94
  5. Step 5: Solve for x
    x = 548,374.94/858.60
  6. Step 6: Final answer
    x = 638.69

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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.