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Finding the Fourth Proportional to 2,139.66, 3,209.39 and 678.62

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Solution

The fourth proportional to 2,139.66, 3,209.39 and 678.62 is: 1,017.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,139.66 : 3,209.39 = 678.62 : x
  2. Step 2: Convert to fraction form
    2,139.66/3,209.39 = 678.62/x
  3. Step 3: Cross multiply
    2,139.66x = 3,209.39 × 678.62
  4. Step 4: Simplify right side
    2,139.66x = 2,177,960.87
  5. Step 5: Solve for x
    x = 2,177,960.87/2,139.66
  6. Step 6: Final answer
    x = 1,017.90

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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.