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Finding the Fourth Proportional to 1,121.82, 1,682.32 and 428.31

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Solution

The fourth proportional to 1,121.82, 1,682.32 and 428.31 is: 642.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.82 : 1,682.32 = 428.31 : x
  2. Step 2: Convert to fraction form
    1,121.82/1,682.32 = 428.31/x
  3. Step 3: Cross multiply
    1,121.82x = 1,682.32 × 428.31
  4. Step 4: Simplify right side
    1,121.82x = 720,558.94
  5. Step 5: Solve for x
    x = 720,558.94/1,121.82
  6. Step 6: Final answer
    x = 642.31

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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.