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Finding the Fourth Proportional to 280.31, 420.15 and 211.61

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Solution

The fourth proportional to 280.31, 420.15 and 211.61 is: 317.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.31 : 420.15 = 211.61 : x
  2. Step 2: Convert to fraction form
    280.31/420.15 = 211.61/x
  3. Step 3: Cross multiply
    280.31x = 420.15 × 211.61
  4. Step 4: Simplify right side
    280.31x = 88,908.47
  5. Step 5: Solve for x
    x = 88,908.47/280.31
  6. Step 6: Final answer
    x = 317.18

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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.