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Finding the Fourth Proportional to 857.70, 1,286.78 and 280.57

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Solution

The fourth proportional to 857.70, 1,286.78 and 280.57 is: 420.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.70 : 1,286.78 = 280.57 : x
  2. Step 2: Convert to fraction form
    857.70/1,286.78 = 280.57/x
  3. Step 3: Cross multiply
    857.70x = 1,286.78 × 280.57
  4. Step 4: Simplify right side
    857.70x = 361,031.86
  5. Step 5: Solve for x
    x = 361,031.86/857.70
  6. Step 6: Final answer
    x = 420.93

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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.