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Finding the Fourth Proportional to 280.71, 421.04 and 85.71

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Solution

The fourth proportional to 280.71, 421.04 and 85.71 is: 128.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.71 : 421.04 = 85.71 : x
  2. Step 2: Convert to fraction form
    280.71/421.04 = 85.71/x
  3. Step 3: Cross multiply
    280.71x = 421.04 × 85.71
  4. Step 4: Simplify right side
    280.71x = 36,086.52
  5. Step 5: Solve for x
    x = 36,086.52/280.71
  6. Step 6: Final answer
    x = 128.56

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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.