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Finding the Fourth Proportional to 857.90, 1,286.68 and 280.64

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Solution

The fourth proportional to 857.90, 1,286.68 and 280.64 is: 420.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.90 : 1,286.68 = 280.64 : x
  2. Step 2: Convert to fraction form
    857.90/1,286.68 = 280.64/x
  3. Step 3: Cross multiply
    857.90x = 1,286.68 × 280.64
  4. Step 4: Simplify right side
    857.90x = 361,093.88
  5. Step 5: Solve for x
    x = 361,093.88/857.90
  6. Step 6: Final answer
    x = 420.90

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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.