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Finding the Fourth Proportional to 2,139.20, 3,208.80 and 1,620.80

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Solution

The fourth proportional to 2,139.20, 3,208.80 and 1,620.80 is: 2,431.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,139.20 : 3,208.80 = 1,620.80 : x
  2. Step 2: Convert to fraction form
    2,139.20/3,208.80 = 1,620.80/x
  3. Step 3: Cross multiply
    2,139.20x = 3,208.80 × 1,620.80
  4. Step 4: Simplify right side
    2,139.20x = 5,200,823.04
  5. Step 5: Solve for x
    x = 5,200,823.04/2,139.20
  6. Step 6: Final answer
    x = 2,431.20

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1.5x scale

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.