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Finding the Fourth Proportional to 280, 385.86 and 209.80

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Solution

The fourth proportional to 280, 385.86 and 209.80 is: 289.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    280 : 385.86 = 209.80 : x
  2. Step 2: Convert to fraction form
    280/385.86 = 209.80/x
  3. Step 3: Cross multiply
    280x = 385.86 × 209.80
  4. Step 4: Simplify right side
    280x = 80,953.43
  5. Step 5: Solve for x
    x = 80,953.43/280
  6. Step 6: Final answer
    x = 289.12

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.