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Finding the Fourth Proportional to 1,286.87, 1,930.71 and 420.98

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Solution

The fourth proportional to 1,286.87, 1,930.71 and 420.98 is: 631.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.87 : 1,930.71 = 420.98 : x
  2. Step 2: Convert to fraction form
    1,286.87/1,930.71 = 420.98/x
  3. Step 3: Cross multiply
    1,286.87x = 1,930.71 × 420.98
  4. Step 4: Simplify right side
    1,286.87x = 812,790.30
  5. Step 5: Solve for x
    x = 812,790.30/1,286.87
  6. Step 6: Final answer
    x = 631.60

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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.