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Finding the Fourth Proportional to 139.80, 209.38 and 85.62

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Solution

The fourth proportional to 139.80, 209.38 and 85.62 is: 128.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.80 : 209.38 = 85.62 : x
  2. Step 2: Convert to fraction form
    139.80/209.38 = 85.62/x
  3. Step 3: Cross multiply
    139.80x = 209.38 × 85.62
  4. Step 4: Simplify right side
    139.80x = 17,927.12
  5. Step 5: Solve for x
    x = 17,927.12/139.80
  6. Step 6: Final answer
    x = 128.23

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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.