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Finding the Fourth Proportional to 209.78, 289.72 and 186.87

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Solution

The fourth proportional to 209.78, 289.72 and 186.87 is: 258.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.78 : 289.72 = 186.87 : x
  2. Step 2: Convert to fraction form
    209.78/289.72 = 186.87/x
  3. Step 3: Cross multiply
    209.78x = 289.72 × 186.87
  4. Step 4: Simplify right side
    209.78x = 54,139.98
  5. Step 5: Solve for x
    x = 54,139.98/209.78
  6. Step 6: Final answer
    x = 258.08

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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.