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Finding the Fourth Proportional to 20,790, 28,690.20 and 12,406.50

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Solution

The fourth proportional to 20,790, 28,690.20 and 12,406.50 is: 17,120.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    20,790 : 28,690.20 = 12,406.50 : x
  2. Step 2: Convert to fraction form
    20,790/28,690.20 = 12,406.50/x
  3. Step 3: Cross multiply
    20,790x = 28,690.20 × 12,406.50
  4. Step 4: Simplify right side
    20,790x = 355,944,966.30
  5. Step 5: Solve for x
    x = 355,944,966.30/20,790
  6. Step 6: Final answer
    x = 17,120.97

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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.