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Finding the Fourth Proportional to 1,286.88, 1,930.59 and 421.13

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Solution

The fourth proportional to 1,286.88, 1,930.59 and 421.13 is: 631.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.88 : 1,930.59 = 421.13 : x
  2. Step 2: Convert to fraction form
    1,286.88/1,930.59 = 421.13/x
  3. Step 3: Cross multiply
    1,286.88x = 1,930.59 × 421.13
  4. Step 4: Simplify right side
    1,286.88x = 813,029.37
  5. Step 5: Solve for x
    x = 813,029.37/1,286.88
  6. Step 6: Final answer
    x = 631.78

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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.