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Finding the Fourth Proportional to 206.72, 309.89 and 78.38

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Solution

The fourth proportional to 206.72, 309.89 and 78.38 is: 117.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.72 : 309.89 = 78.38 : x
  2. Step 2: Convert to fraction form
    206.72/309.89 = 78.38/x
  3. Step 3: Cross multiply
    206.72x = 309.89 × 78.38
  4. Step 4: Simplify right side
    206.72x = 24,287.63
  5. Step 5: Solve for x
    x = 24,287.63/206.72
  6. Step 6: Final answer
    x = 117.49

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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.