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Finding the Fourth Proportional to 139.80, 209.57 and 71.30

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Solution

The fourth proportional to 139.80, 209.57 and 71.30 is: 106.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.80 : 209.57 = 71.30 : x
  2. Step 2: Convert to fraction form
    139.80/209.57 = 71.30/x
  3. Step 3: Cross multiply
    139.80x = 209.57 × 71.30
  4. Step 4: Simplify right side
    139.80x = 14,940.94
  5. Step 5: Solve for x
    x = 14,940.94/139.80
  6. Step 6: Final answer
    x = 106.87

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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.