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Finding the Fourth Proportional to 1,286.94, 1,930.72 and 421.25

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Solution

The fourth proportional to 1,286.94, 1,930.72 and 421.25 is: 631.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.94 : 1,930.72 = 421.25 : x
  2. Step 2: Convert to fraction form
    1,286.94/1,930.72 = 421.25/x
  3. Step 3: Cross multiply
    1,286.94x = 1,930.72 × 421.25
  4. Step 4: Simplify right side
    1,286.94x = 813,315.80
  5. Step 5: Solve for x
    x = 813,315.80/1,286.94
  6. Step 6: Final answer
    x = 631.98

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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.