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Finding the Fourth Proportional to 209.66, 289.38 and 139.72

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Solution

The fourth proportional to 209.66, 289.38 and 139.72 is: 192.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.66 : 289.38 = 139.72 : x
  2. Step 2: Convert to fraction form
    209.66/289.38 = 139.72/x
  3. Step 3: Cross multiply
    209.66x = 289.38 × 139.72
  4. Step 4: Simplify right side
    209.66x = 40,432.17
  5. Step 5: Solve for x
    x = 40,432.17/209.66
  6. Step 6: Final answer
    x = 192.85

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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.