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Finding the Fourth Proportional to 12,420, 17,139.60 and 6,831

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Solution

The fourth proportional to 12,420, 17,139.60 and 6,831 is: 9,426.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    12,420 : 17,139.60 = 6,831 : x
  2. Step 2: Convert to fraction form
    12,420/17,139.60 = 6,831/x
  3. Step 3: Cross multiply
    12,420x = 17,139.60 × 6,831
  4. Step 4: Simplify right side
    12,420x = 117,080,607.60
  5. Step 5: Solve for x
    x = 117,080,607.60/12,420
  6. Step 6: Final answer
    x = 9,426.78

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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.