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Finding the Fourth Proportional to 209.78, 289.29 and 143.49

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Solution

The fourth proportional to 209.78, 289.29 and 143.49 is: 197.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.78 : 289.29 = 143.49 : x
  2. Step 2: Convert to fraction form
    209.78/289.29 = 143.49/x
  3. Step 3: Cross multiply
    209.78x = 289.29 × 143.49
  4. Step 4: Simplify right side
    209.78x = 41,510.22
  5. Step 5: Solve for x
    x = 41,510.22/209.78
  6. Step 6: Final answer
    x = 197.88

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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.