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Finding the Fourth Proportional to 857.89, 1,286.82 and 280.75

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Solution

The fourth proportional to 857.89, 1,286.82 and 280.75 is: 421.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.89 : 1,286.82 = 280.75 : x
  2. Step 2: Convert to fraction form
    857.89/1,286.82 = 280.75/x
  3. Step 3: Cross multiply
    857.89x = 1,286.82 × 280.75
  4. Step 4: Simplify right side
    857.89x = 361,274.72
  5. Step 5: Solve for x
    x = 361,274.72/857.89
  6. Step 6: Final answer
    x = 421.12

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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.