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Finding the Fourth Proportional to 1,080.80, 1,620.40 and 431.20

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Solution

The fourth proportional to 1,080.80, 1,620.40 and 431.20 is: 646.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,080.80 : 1,620.40 = 431.20 : x
  2. Step 2: Convert to fraction form
    1,080.80/1,620.40 = 431.20/x
  3. Step 3: Cross multiply
    1,080.80x = 1,620.40 × 431.20
  4. Step 4: Simplify right side
    1,080.80x = 698,716.48
  5. Step 5: Solve for x
    x = 698,716.48/1,080.80
  6. Step 6: Final answer
    x = 646.48

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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.