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Finding the Fourth Proportional to 1,286.12, 1,929 and 420.44

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Solution

The fourth proportional to 1,286.12, 1,929 and 420.44 is: 630.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.12 : 1,929 = 420.44 : x
  2. Step 2: Convert to fraction form
    1,286.12/1,929 = 420.44/x
  3. Step 3: Cross multiply
    1,286.12x = 1,929 × 420.44
  4. Step 4: Simplify right side
    1,286.12x = 811,028.76
  5. Step 5: Solve for x
    x = 811,028.76/1,286.12
  6. Step 6: Final answer
    x = 630.60

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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.