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Finding the Fourth Proportional to 1,286.85, 1,930.26 and 421.16

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Solution

The fourth proportional to 1,286.85, 1,930.26 and 421.16 is: 631.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.85 : 1,930.26 = 421.16 : x
  2. Step 2: Convert to fraction form
    1,286.85/1,930.26 = 421.16/x
  3. Step 3: Cross multiply
    1,286.85x = 1,930.26 × 421.16
  4. Step 4: Simplify right side
    1,286.85x = 812,948.30
  5. Step 5: Solve for x
    x = 812,948.30/1,286.85
  6. Step 6: Final answer
    x = 631.74

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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.