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Finding the Fourth Proportional to 209.78, 289.51 and 139.97

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Solution

The fourth proportional to 209.78, 289.51 and 139.97 is: 193.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.78 : 289.51 = 139.97 : x
  2. Step 2: Convert to fraction form
    209.78/289.51 = 139.97/x
  3. Step 3: Cross multiply
    209.78x = 289.51 × 139.97
  4. Step 4: Simplify right side
    209.78x = 40,522.01
  5. Step 5: Solve for x
    x = 40,522.01/209.78
  6. Step 6: Final answer
    x = 193.16

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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.