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Finding the Fourth Proportional to 280.90, 421.35 and 209.21

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Solution

The fourth proportional to 280.90, 421.35 and 209.21 is: 313.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.90 : 421.35 = 209.21 : x
  2. Step 2: Convert to fraction form
    280.90/421.35 = 209.21/x
  3. Step 3: Cross multiply
    280.90x = 421.35 × 209.21
  4. Step 4: Simplify right side
    280.90x = 88,149.59
  5. Step 5: Solve for x
    x = 88,149.59/280.90
  6. Step 6: Final answer
    x = 313.82

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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.