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Finding the Fourth Proportional to 1,287.12, 1,930.62 and 409.56

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Solution

The fourth proportional to 1,287.12, 1,930.62 and 409.56 is: 614.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.12 : 1,930.62 = 409.56 : x
  2. Step 2: Convert to fraction form
    1,287.12/1,930.62 = 409.56/x
  3. Step 3: Cross multiply
    1,287.12x = 1,930.62 × 409.56
  4. Step 4: Simplify right side
    1,287.12x = 790,704.73
  5. Step 5: Solve for x
    x = 790,704.73/1,287.12
  6. Step 6: Final answer
    x = 614.32

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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.