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Finding the Fourth Proportional to 18,990, 28,485 and 5,139

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Solution

The fourth proportional to 18,990, 28,485 and 5,139 is: 7,708.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    18,990 : 28,485 = 5,139 : x
  2. Step 2: Convert to fraction form
    18,990/28,485 = 5,139/x
  3. Step 3: Cross multiply
    18,990x = 28,485 × 5,139
  4. Step 4: Simplify right side
    18,990x = 146,384,415
  5. Step 5: Solve for x
    x = 146,384,415/18,990
  6. Step 6: Final answer
    x = 7,708.50

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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.