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Finding the Fourth Proportional to 280.25, 420.27 and 85.21

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Solution

The fourth proportional to 280.25, 420.27 and 85.21 is: 127.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.25 : 420.27 = 85.21 : x
  2. Step 2: Convert to fraction form
    280.25/420.27 = 85.21/x
  3. Step 3: Cross multiply
    280.25x = 420.27 × 85.21
  4. Step 4: Simplify right side
    280.25x = 35,811.21
  5. Step 5: Solve for x
    x = 35,811.21/280.25
  6. Step 6: Final answer
    x = 127.78

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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.