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Finding the Fourth Proportional to 858.35, 1,287.87 and 511.85

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Solution

The fourth proportional to 858.35, 1,287.87 and 511.85 is: 767.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.35 : 1,287.87 = 511.85 : x
  2. Step 2: Convert to fraction form
    858.35/1,287.87 = 511.85/x
  3. Step 3: Cross multiply
    858.35x = 1,287.87 × 511.85
  4. Step 4: Simplify right side
    858.35x = 659,193.70
  5. Step 5: Solve for x
    x = 659,193.70/858.35
  6. Step 6: Final answer
    x = 767.98

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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.